Thanks to late-season charges that led to playoff berths in 2007 and 2009, the Colorado Rockies have developed a reputation as a team of slow starters and fast finishers. No player exemplifies this attribute better than Troy Tulowitzki, whose current .304/.375/.549 (BA/OBP/SLG) line, combined with stellar defense at shortstop, should earn him some MVP votes.
"It was a tale of two seasons" is a sports writing cliche you'll typically see only from a lazy hack (this usage notwithstanding), but for Tulo, it's almost always true. While the 26-year-old is usually a good player before the All-Star break, he becomes a superstar after it. And this transformation happens every single year.
His half-season splits certainly seem enormous at first glance, but we still need to consult the data. (For all we know, maybe every MLB player hits 20 percent better in the second half of the season.) This year, MLB clubs have a .731 OPS after the break and a .711 OPS before it, but that's a tiny gap compared to Tulo's. And if you look at the past three seasons, the league has hit almost exactly the same in the first half (.731 OPS) as the second (.735). The Rockies' players show a similar split over the past three years, so this is not a Coors Field issue. Therefore, Tulo is an outlier, and the most remarkable thing about these splits might just be how consistent he's been in producing them, particularly the past three years. His first- and second-half numbers are almost identical in each season.
So what changes after the All-Star break? What is Tulowitzki doing in the second half of the season that he isn't doing in the first half? To try to get to the bottom of this, I analyzed his Pitch F/X data for both halves of his 2011 season using some fascinating visuals.