It was September 2008. Bryce Harper was 15 years old. The Tampa Bay Rays were on their way to the playoffs in their first-ever winning season. And of the 15 fly balls that a 27-year-old 4A player whom most fans had never heard of hit after August 31, a third of them flew over the fence. His name was Ben Zobrist, and the next season he emerged as one of the best players in baseball.
Fast-forward a year to the end of the 2009 season. Another unremarkable player in his late 20s posted a .944 OPS from September 1 on. A man who had once played for four different teams in one season hit 10 home runs in just 109 at-bats. His name was Jose Bautista, and in 2010 he belted 54 home runs.
I noticed this trend after the 2010 season, and so I embarked on the first of what became my annual trip in search of the "next Jose Bautista." To do this, I look at the September leaderboard for home runs, home runs per fly ball, and isolated power (ISO) to see if anyone out of the ordinary jumps out. And quite often, they do.
For 2011, I picked Michael Morse, and he rewarded my faith by hitting 31 homers. A year later I called Brent Morel the next next Jose Bautista, and he repaid me by hitting .177 without going yard once. Call him the exception that proves the rule.
Last year, I called Jason Castro the next, next, next Bautista, and I'm proud to call that one a success. Castro hit 18 homers in 120 games while playing the toughest position in the field, and his 130 wRC+ put him in the same neighborhood as Giancarlo Stanton, Carlos Beltran, and even Bautista himself. (The big breakout story of 2013 was of course Chris Davis. As I noted a year ago, he fit the mold too, but I did not think his September power surge was as out of character as Castro's.)
If using September power numbers to predict the next season's performance sounds overly simplistic, you're right. A few dozen at-bats aren't nearly enough to get a good read on a player, especially if you're projecting him to do something far beyond everything else he's done in his career. But if you suspend your disbelief for a moment, it makes some logical sense: If a guy is playing at a level he's never reached before, even in a small sample size, it could be an indication that something has clicked.
Looking at last year's September leaderboards, there isn't a single player who pops out as having Bautista-like surge. That said, here's a list of the five best candidates to be the next, next, next, next Jose Bautista.