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Looking for potential impact fantasy players in September roster expansions is a dicey proposition because of all the various factors involved.

1. Players have to be on the 40-man roster in order to be called up, and teams don't necessarily like to put players on the 40-man until they have to. Granted, some teams have some dead weight at the back end that they could jettison to create room. However, it means a lot of the bigger names might have to wait until next season.

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2. Postseason play in the minors delays the call-ups of some players. For example, the Angels might not want to call up some of their guys from Triple-A like Brandon Wood, because his Salt Lake club made the playoffs.

3. Pitching prospects, especially starters, might have already reached or be close to the innings limits that their teams have set for them, even though their performances might merit a couple of September starts. Additionally, pitchers who have been starters in the big leagues that do see major league time in September are sometimes relegated to pitching out of the bullpen.

4. Some teams are not fans of large-scale call-ups. As Tigers manager Jim Leyland told the team Web site, "I've never liked to overload [the roster] in September too much. You kind of base it on what you think makes the best sense."

5. The types of players that are called up are not always intriguing prospects, but more like third catchers, extra utility infielders, extra bullpen arms, or other veterans. Sure, the expanded rosters help out big league managers by giving them more players to use for strategic purposes, but that doesn't do much for fantasy teams.

6. Many players who are called up have already seen time in the big leagues this season and are getting another look, or are returning from injury. Thus, the cream of that crop is usually already on the bench of a fantasy team's roster already.

And finally, the most important factor of all -- potential playing time.

Just because a player is called up, it doesn't mean he's going to get enough playing time to be a big fantasy factor. In mixed leagues, a player getting only part-time at-bats can put an owner at a disadvantage. While AL or NL-only players can get away with that a bit more, you want your hitters to be playing five or six games a week in mixed leagues.

If a player was going to get a good amount of playing time over the balance of the season, there's a good chance he has already been called up and his team hasn't waited until rosters expand, such as the Rangers did with Nelson Cruz, or the Red Sox did with Clay Buchholz last season (calling him up in mid-August.)

The bottom line is expecting some fantasy statistical saviors might leave you disappointed. For keeper league players, however, this is a chance to potentially stash away a player or two for next season, depending on your league rules.

Let's take a look at some potential call-ups by team and see whom we can identify as the ones that have the combination of talent and potential role that could make them useful fantasy options for the final four weeks. It's a bit of a crapshoot, but I'll try to make some semi-educated guesses. Remember, it's all about getting in the lineup or the rotation.

Arizona Diamondbacks: If the Diamondbacks had any potential impact fantasy hitters ready for big-league duty, they would have been up already. The returns of Justin Upton and Max Scherzer need to be watched closely as Mark Reynolds could slide to second base to open up a regular spot for Upton in the lineup and Scherzer could see four or five starts down the stretch if the team decides to put him in the rotation at the expense of Yusmeiro Petit. Scherzer starting every fifth day is a definite sleeper in all formats. Jamie D'Antona might also get another look, but as a third catcher/utility player, he won't get to play enough to be useful.

Atlanta Braves: The Braves might take a look at outfielders Josh Anderson and Jordan Schafer, who are certainly fantasy-worthy if they get some playing time; Anderson because of his stolen-base potential and Schafer for his all-around game. The likely trade of Mark Kotsay could open up some at-bats, although Brandon Jones will be in the mix as well, so we'll have to see how this situation plays out. Other than that, expect players like infielder Brent Lillibridge to be called up for depth.

Baltimore Orioles: The big question here is the status of the top hitting prospect in the minors, Matt Wieters, who is already ticketed for the Arizona Fall League. The Baltimore Sun reported on Sunday that manager Dave Tremblay said Wieters would not be promoted to the big leagues this season, so it appears he won't make his debut until sometime in 2009.

Another intriguing development is the return of Chris Ray from Tommy John surgery. Ray threw at Double-A on Tuesday, and though it's not likely he'll be closing games for the O's in the last couple of weeks, it's at least a possibility. The O's might have some interesting pitching options if they choose to give Chris Tillman, David Hernandez or Brad Bergesen any starts down the stretch.

For some reason, Nolan Reimold has been stuck at Double-A all season, but he projects as a legitimate big league outfielder, so pay attention if it looks like he might get some at-bats.

Boston Red Sox: Outside of the return of Bartolo Colon, the Red Sox are expected to call up a bunch of bullpen arms like Chris Smith and Devern Hansack and other bench players for depth like Chris Carter and Jonathan Van Every, none of whom will see much playing time. Will Michael Bowden be one of them for keeper league players to stash away? It's certainly possible they might try him in the pen, but unlikely. The same goes for Double-A closer Daniel Bard.

Chicago Cubs: Like other contending teams, any players they add to the roster are likely just going to be for roster depth. Their lineup is set, their rotation is set and their bullpen is set, negating any fantasy impact for players who are called up.

Chicago White Sox: Even if Jerry Owens and his stolen base potential make their way back to the White Sox roster, there's just no room for him to play. If the White Sox decide to give prospects Jack Egbert or Aaron Poreda, or knuckleballer Charlie Haeger some starts, they are worth a look in AL-only leagues, but not in mixed play. However, the team appears settled on Lance Broadway and Clayton Richard as the back of the rotation at the moment, so there aren't any starting jobs available. Chris Getz will return as a backup infielder.

Cincinnati Reds: Homer Bailey has a strained MCL, which means his return to the big leagues could be on hold for a bit. The team is expected to bring up some relievers and some journeyman starters, with a small chance that their 2006 first-round pick, outfielder Drew Stubbs, gets a look. Stubbs has some speed if he gets some at-bats.

Cleveland Indians: The Indians are toying with the idea of a six-man rotation for September to look at some players, which means Aaron Laffey could get another chance. A very interesting name to watch though is left-hander David Huff, a potential middle-of-the-rotation starter who has excelled at both Double-A and Triple-A this season. He's at 141 innings, so it's not out of the realm of possibility he gets a late-season audition if the club wants to add him to the 40-man roster. Closer prospect Jonathan Meloan could also get a look in a middle relief role. The club is likely to sign a free-agent closer in the offseason, putting his viability as a keeper for '09 in doubt.

Outfielder Trevor Crowe might see some action, but he doesn't bring much to the table fantasy-wise, and is a fourth outfielder at best. There are also the obvious additions of Victor Martinez and Travis Hafner when they are healthy. First baseman Matt LaPorta and third baseman Wes Hodges are not expected to get the call, but you never know.

Colorado Rockies: The Rockies have quietly moved to within six games of the division lead, so they're not going to play like they are out of it just yet. Names like Joe Koshansky undoubtedly will make an appearance, but there is no room at the corner spots. Other names to watch closely, if they appear, would be future closer Casey Weathers and outfielder Dexter Fowler, especially if Willy Taveras is moved in a waiver deal.

Detroit Tigers: Leyland says he's going to play his regular team down the stretch, so even though names like first baseman Jeff Larish, outfielder Brent Clevlen and infielder Michael Hollimon likely puts on a big league uniform again, they won't have any use in fantasy. Dontrelle Willis is not a fantasy factor until he proves otherwise, even if his latest forearm injury heals in time for him to make some starts late in the season.

Florida Marlins: The return of Andrew Miller and the Marlins' debut of Cameron Maybin highlight the potential call-ups. Maybin could be the starting center fielder in 2009, so keeper leaguers might want to grab him now if their league rules allow. He might not hit for a good average to start, but he will bring the speed right out of the gate. His Double-A team is headed to the playoffs, so he won't be up right away.

Houston Astros: The only player of fantasy interest likely to be on the list is catcher J.R. Towles. He's a better hitter than what he showed in his first stint, but there are likely better catchers available in your free-agent pool if you need one.

Kansas City Royals: The Royals might take a look at slugging first baseman Kila Ka'aihue during the past few weeks, as there really is no reason for them to keep running Ross Gload out there. If not Ka'aihue, then perhaps Ryan Shealy, but bet on Ka'aihue, who hasn't missed a beat since being promoted to Triple-A. Ka'aihue is an intriguing short-term option in all formats, even if long-term he might just be a platoon player at best.

Additionally, Carlos Rosa might have some value in deep AL leagues if he joins the Royals rotation for the stretch run. None of the other pitchers the Royals are likely to call up should have much of an impact during the next season.

Los Angeles Angels: The Angels are expected to add Bobby Wilson as a third catcher and a few bullpen arms with no fantasy value. Brandon Wood will be back up after the playoffs are finished, but he isn't going to play enough to be of any use this season, nor will any of the other likely call-ups like Matt Brown or Terry Evans as the Angels say they plan to keep playing the regular roster.

Los Angeles Dodgers: The return of Blake DeWitt and Chin-lung Hu and starting pitching prospect James McDonald highlight the Dodgers' potential call-ups, which also includes a backup outfielder and a third catcher. They are very careful about how they use their 40-man roster, only putting a player on it when it is absolutely necessary. Scott Elbert might get a look as a lefty reliever if the team clears a 40-man spot. McDonald is an interesting prospect, but the rotation is full.

Milwaukee Brewers: The big name here is obviously Mat Gamel, who has moved to Triple-A, and is under definite consideration to come up, so that is a situation that should be watched closely. This will be your chance to tuck him away.

Last season, the Brewers added about a half dozen players strictly as roster depth in their playoff push: an extra catcher, two extra bullpen arms, a couple of extra outfielders, that sort of thing. It looks to be the same this year. General manager Gord Ash told the team Web site, "When you're 'in it,' as we are, you're looking for parts to help you win a game. Nobody is going to come up and play a position to audition for next year. It's much different. The guys who come up know they might sit for a few weeks and then get one at-bat or throw to one hitter. But that could be the turning point in a game."

Tony Gwynn Jr., Jay Gibbons and the return of Russell Branyan from injury are also possibilities for additional depth, but they won't play enough to merit fantasy consideration. Shortstop prospect Alcides Escobar might also get a look to provide speed and defense off of the bench, and should then be stashed away in dynasty leagues where he's not already on a roster.

Minnesota Twins: Who the Twins call up will strictly be for depth purposes, though any of their young pitchers like Brian Duensing, Kevin Mulvey or Philip Humber always bear watching, especially if they get some starts. Outfielder Jason Pridie is a position player to have on your radar if he somehow gets some at-bats, which is doubtful.

New York Mets: Jon Niese is going to be joining the rotation in place of John Maine on Sept. 2, making him a sleeper down the stretch. Other than that, if there were any players who could have decent fantasy value in September, they would have been called up already given all their injuries.

New York Yankees: The Yankees are likely to try out several bullpen arms, as well as bring back Melky Cabrera, who won't be returning to a starting job. Phil Hughes also returns, but he hasn't been pitching well at Triple-A and can't be counted on to help your team down the stretch. He's more someone to stash away for 2009 as a speculative play. Top hitting prospect Austin Jackson is not likely to be promoted, but keeper league players should be on alert, just in case.

Oakland A's: The A's rotation is full right now, even given their recent injuries, so starting pitching prospects Trevor Cahill, Brett Anderson and Vin Mazzaro are all likely going to have to wait. Outfielders Travis Buck and Matt Murton would both merit modest fantasy interest if either was in line for regular September at-bats. Landon Powell is likely to be called up as the third catcher and might get a little time to audition for the backup role next season.

Philadelphia Phillies: The Phillies have a reasonably set rotation right now, so even though they might call up a pitcher like J.A. Happ, or perhaps Carlos Carrasco (who would need to be added to the 40-man), it likely won't be to start unless something changes. This is another team that looks to add some extra arms for the pen and some additional roster depth, but that's about it.

Pittsburgh Pirates: There are two bats that could get both a call-up and some playing time: Andrew McCutchen and Steve Pearce, and one of them should get at-bats in September. Considering the Jason Michaels/Doug Mientkiewicz tandem in right field, it would seem that Pearce should get some at-bats there, but his numbers have been underwhelming this season, so he might not be able to do much with them. McCutchen's situation is a bit more complicated with left and center occupied, as he doesn't have the arm for right, but his power/speed combination demands attention when he gets to the big leagues, because if he's up, he's going to play.

San Diego Padres: The Padres are lacking in prospects who could make any kind of decent immediate impact, especially on the hitting side, and they are careful about watching their pitcher's workloads, so starters like Wade LeBlanc and Will Inman probably won't make their big league debuts. General manager Kevin Towers has already ruled LeBlanc out due to his innings. Second base prospect Matt Antonelli is hitting just .215, so he's a nonfactor.

San Francisco Giants: They've started their youth movement already, and don't expect any of their big names such as pitchers Tim Alderson or Madison Bumgarner to get a look.

Seattle Mariners: Brandon Morrow will be back up as a starting pitcher, but he has not looked good in that role at Triple-A, despite one game with a gaudy strikeout total. He's a high-risk, high-upside play at best for the balance of the season. The M's have a few other prospects they could call up, like catcher Rob Johnson, but they're already trying to look at the young players they have now, so playing time would be limited.

St. Louis Cardinals: Top prospect Colby Rasmus has returned to the field at Triple-A after missing a month with a knee injury, but manager Tony LaRussa told the team Web site he is unlikely to get the call. "He hasn't been playing," La Russa said. "We haven't had the meeting officially, but I just don't think [he will be called up]. He hasn't earned it. Injuries are injuries, but you can't reward somebody because of it."

It's possible the team could call up pitcher Jess Todd, who has really put himself on the map this season, but as I've said before, I think he's ultimately a bullpen arm in the big league that likely won't have a lot of fantasy value.

Tampa Bay Rays: The answer to the big David Price question appears to be that he gets his feet wet in the bullpen. Good to stash away for 2009, bad for his fantasy value in September. Other starting pitchers like Wade Davis, Jeff Niemann and Mitch Talbot could all see some time in the pen, but the Rays' Triple-A club is in the playoffs, so that delays some call-ups. Jonny Gomes returns, and Fernando Perez and his stolen base potential could debut but likely will not see a ton of playing time. The same goes for catcher John Jaso. Both are potential future fantasy-worthy players. The forgotten-by-most Dan Johnson can hit, and he could squeak out a few DH at-bats from Cliff Floyd, but again, with the Rays in a playoff race, most of their call-ups will be for depth purposes.

Texas Rangers: With Nelson Cruz already up, the Rangers are expected to promote catchers Max Ramirez and Taylor Teagarden when the playoffs are finished, but not enough playing time will be available for them to have September impact. Starter Brandon McCarthy is actually going to be activated to start on Saturday, but should be avoided. Shortstop Elvis Andrus, and pitchers Neftali Feliz and Derek Holland are not expected to get a big league summons.

Toronto Blue Jays: Three of the Jays best prospects, outfielder Travis Snider, catcher J.P. Arencibia and pitcher Brett Cecil, are not going to be called up, according to general manager J.P. Ricciardi. The team likely will bring Shaun Marcum back and promote a couple of relief arms, a catcher and a utility infielder like Kevin Melillo. In other words, it's not a lot to see for fantasy owners outside of Marcum, who has to show he's past his elbow woes first.

Washington Nationals: There are not a lot of options for the Nats to call up that would be of any use in fantasy. Outfield prospect Justin Maxwell has had a horrible season at Double-A, as has starter Ross Detwiler at high Class-A.

We'll keep you posted as the transactions happen and what the fantasy ramifications are.

Jason Grey is a graduate of the MLB Scouting Bureau's Scout Development Program and has won two Tout Wars titles, one LABR title and numerous other national "experts" competitions.