August 19, 2015
Average Exit Velocity
In the first season of the Statcast era, batted-ball exit velocity has been an exciting statistic for baseball fans to get our hands on, but before we have a full season of data under our belts it's difficult to draw any conclusions. Still, here's an attempt to examine how exit velocity has affected performance at the plate with some of the numbers that we have. Below are the five players who most increased and the five players who most decreased their batted-ball velocity in July, compared to June (with at least 30 batted balls in each month). Also included are the biggest exit-velocity movers from June to see how their average exit velocity fared in July.
This is by no means a scientific study, as the small samples and arbitrary markers of calendar months will show you. However, it's still interesting to look at how big swings in average exit velocity have impacted different aspects of offensive performance. I look at BABIP and ISO because they're the best way to get a back-of-the-envelope estimate of what a hitter does when he puts the ball in play: his ability to get a hit, and his ability to hit for power. The quality-of-contact percentages break down how a hitter increased or decreased his velocity. They show, for example, if a player increased his hard-hit balls at the expense of his medium-hit balls or at the expense of his softest-hit balls. I didn't include trajectory data like line-drive percentage because it seems that the two don't correlate. I do often reference it, however, because line-drive percentage still has a great effect on a hitter's performance independent of his exit velocity.
Changes in BABIP were often unpredictable. Changes in ISO were much more related with changes in a hitter's exit velocity. Also of note are two exit-velocity movers from June who showed up on this chart in July: After JJ Hardy increased his average exit velocity and Mike Moustakas decreased his average exit velocity, both players moved in the opposite directions in July.
Asche's BABIP decreased in July despite an enormous increase in his exit velocity. This can't be chalked up to much more than random variation, as Asche's line-drive percentage also increased 4 percentage points in July. He hit just about the same rate of fly balls and fewer ground balls. Most of the change in quality of contact came from Asche's soft balls and was transferred to his hard.
Kinsler's BABIP went from .288 in June—on par with his career .286 BABIP—to .404 in July, which was most likely due to his jump in average exit velocity and a four-point increase in line-drive percentage. One or both of these factors also heavily affected Kinsler's ISO, as he had nine more extra-base hits in July than in June. Kinsler's increase in contact was effective, as it migrated entirely to his hard percentage instead of his medium percentage.
Castellanos hammered the ball 6½ mph harder on average in July. Although his BABIP decreased to .300 (partially explained by a three-point drop in line-drive percentage), he was a better overall offensive player for it, as his OPS increased 120 points. This was largely due to the six home runs he hit in the month, which caused the dramatic increase in ISO.
Duda's BABIP dropped from bad in June to awful in July, which is probably partly due to bad luck and partly due to a 3.5-point drop in his line-drive percentage. But when he got ahold of one, he got ahold of one, as he hit eight home runs during the month. Six of those were part of Duda's streak of eight consecutive hits that went for home runs, which was perhaps the best illustration of Duda's all-or-nothing month. It was either very good or very bad for Duda, and the increase in both his hard and soft percentages shows this as well.
Moustakas' chart from last month is shown because he was an exit-velocity mover in June, too. His performance is, obviously, pretty counterintuitive. His exit velocity dropped by 6.16 mph in June, then rebounded by almost exactly the same amount in July. Yet, while his BABIP went up a bit in June, it crashed in July. His ISO barely budged in July. This is a tough one to figure out, since his line-drive percentage actually went up a bit in July.
Espinosa's exit velocity dramatically decreased in July, and his BABIP and ISO reflected that, although not as much as one might think, especially given a 16-point drop in his line-drive percentage as well.
Hardy, another double exit-velocity mover, had a puzzling month. His exit velocity decreased in July by even more than it had increased in June, and his BABIP went from unsustainably high to unsustainably low. Moreover, his ISO jumped in the month. Hardy still managed to hit quite a few balls over 100 mph—10 of them, as the chart shows, three of which went for home runs—but he had many more softly hit ones, including three under 40 mph, which dragged his overall average down.
Perez's BABIP fell from bad to worse in June. However, despite a small decrease in line-drive percentage as well, it didn't go down as much as it could have, possibly because of more of his contact migrated from medium to soft than from hard to soft.
Mercer's ISO bore the brunt of his nearly 5 mph drop in exit velocity while his BABIP didn't budge, which is probably a fluke, given how high it already is and given that no other aspect of Mercer's batted-ball profile really improved. In fact, it survived a 10-point increase in his ground-ball rate. Overall, however, Mercer did struggle at the plate, as his lack of slugging and increased strikeouts made him a less effective offensive player overall.
Duffy was able to make some gains in BABIP—which helped his overall average, since his strikeout rate remained around the same—due to a six-point jump in line-drive percentage. However, after jumping by nearly 4 mph in June, his exit velocity fell back almost 5 mph in July, and his ISO reflected that change. Duffy has had an ISO hovering around .100-.115 in most months, except for June, when it was more than twice that and when his exit velocity was near 91 mph.
June's Biggest Gainers
After a huge jump in June to become baseball's hardest hitter for that month, Cespedes fell back a bit in July, but still managed to retain and improve upon some of the strides he had made. Interestingly, although his ISO barely budged in June, it rocketed upwards in July (helped by the eight home runs he hit in the month), even though his batted-ball velocity fell by almost 3 mph. Also interesting is the anatomy of Cespedes's drop: Both his hard contact and soft contact increased. Perhaps the increase in hard contact helped Cespedes bring up his number of extra base hits, but the increase in soft contact contributed to a higher number of softly hit balls for outs.
The rub on Aviles last month was a 17-point jump in ground balls, which caused his overall offense to decline. However, the rough times continued for Aviles despite maintaining his gains in exit velocity and bringing his ground-ball rate down by about eight percentage points and his line drive rate up by about four. There's obviously quite a bit of flukiness here, as no one goes very long with a .105 BABIP. Still, despite the staidness of his overall average exit velocity, his sharp decline in hard contact and increase in medium contact is worth noting.
Did not qualify
After being stuck in the basement since the proliferation of the shift, Texeira's BABIP is finally experiencing some liftoff. Texeira is pulling the ball more than ever this season, but his BABIP has risen with each month. Texeira's average exit velocity, after dropping nearly 7 mph from April to May, has almost made its way all the way back to the 91.44 he boasted in the season's first month. While his ISO then was nearly identical at .392, July's Teixeira is a better version of the first baseman. He now pulls the ball less and hits more line drives. Despite Texeira's fairly small change in overall average exit velocity, his sharp increase in hard percentage is notable.
Steven Souza Jr.
Did not qualify
Did not qualify
June's Biggest Losers
Despite increasing his line drive percentage by three percentage points, increasing his fly ball percentage, also by three points, while keeping his HR/FB ratio fairly constant and hitting the ball up the middle more, Dozier's offense crashed as his exit velocity came down by just less than 2 mph. While Dozier was probably lucky with batted balls in June, given his consistent BABIP and huge exit velocity drop, he most likely got unlucky in that respect in July. Dozier's quality-of-contact change is interesting, as an even steeper increase in hard percentage (despite a smaller decrease in overall exit velocity) caused a sharp decline in his offense.
Did not qualify