While most teams have played around 25 percent of their 2013 schedule, the reality is that taking a player's stats at face value is still generally a mistake. Six weeks of baseball is not enough for the normal ups and downs to have evened out, and the leaderboards of mid-May will not resemble the numbers at the end of the season. At this point in the year, you are almost always better off looking at a player's track record than his 2013 performance.
However, there is an exception that proves the rule. There are some cases in which a player is showing a pretty dramatic change in skills, and that change should cause you to discount his past performance and put a little more faith in what he's doing right now. Cliff Lee in 2008 is perhaps the most extreme example of this effect, as he showed up to camp with more velocity, a new cut fastball and the ability to throw the ball wherever he wanted, which turned him from a back-end starter into a legitimate Cy Young contender.
There's no one having quite that dramatic of a conversion, but here are three players who have made a distinct shift that should give us some reason to think they might just keep this up for the remainder of the year.