Let’s take a look at what the pitch-performance data shows.
Bryce Harper: Performance vs Breaking Ball Away
Through much of last season, Harper had issues against a specific type of pitch: breaking balls on the outer-half of the plate, or off the outside corner.
Harper vs Breaking Balls on Outer Half
Harper had really good numbers when he made contact with that pitch, but making contact was an issue.
He missed on 43 percent of his swings against curves and sliders to that location (the major-league average for non-pitchers was 33 percent) and put only 31 percent of them in play (MLB average was 41 percent). Both of those ranked in the bottom 16 among the 144 hitters who qualified for the batting title last season.
Until he proves that he can hit them, Harper will likely see breaking balls to that area. Last season, Harper saw among the lowest rates of fastballs in the majors (53 percent if you include sinkers, splitters and cutters) and a top-20 rate of breaking pitches (32 percent).
Mike Trout: vs Left-Handed Pitching
It’s hard to find areas of improvement for someone who was a 10-win player per the Wins Above Replacement stat last season, but here’s one area where Trout may still be developing: his performance against left-handed pitching.
Trout hit .267 against lefties last season, with a .368 on-base percentage and .493 slugging percentage (.862 OPS). Those numbers, while not bad, are not the dominant ones you would expect from someone with numbers like Trout.
Trout vs Left-Handed Pitching
Compared to Other Notable RHB in 2012
The batting average, in particular, ranked below average for a right-handed hitter against left-handed pitching. It was the lowest among the eight AL righties who hit at least .300 (though only two points below Adrian Beltre).
Inside Edge tracks a stat called "hard-hit rate" which reflects how often a batter hits the ball hard. Trout had a well-hit ball in 27 percent of his at-bats against righties, the 12th-best rate in the majors (out of 144). His 18 percent rate against lefties ranked 101st.
Even taking strikeouts out of the mix and Trout’s hard-hit rate against lefties is 24 percent, well short of his 36 percent rate against righties.
How did lefties get Trout out? The pitch he had the most issues with from a statistical perspective were fastballs (excluding cutters, sinkers and splitters).
Trout missed on 19 percent of swings against fastballs, a little bit above the major-league rate of 16 percent, and his 32 percent in-play rate was below the big-league average of 43 percent.
This was also a way to keep Trout in the ballpark. He saw 451 fastballs from lefties and hit only one home run.