If there is one thing that is absolutely certain about Casey Kotchman’s game, the first baseman hits a lot of ground balls. To date this season, 55.8 percent of Kotchman’s batted balls have been on the ground, which is in line with his 53.3 percent career average. The average qualified first baseman hits ground balls at a rate of 42.9 percent, nearly 13 percent less than Kotchman.
One might surmise that ground balls are not a great means of ball transport for a first baseman with 10 stolen bases over nearly 2,500 plate appearances. However, Matthew Carruth recently researched BABIP on ground balls based on speed score at Fangraphs, and found speed affected BABIP far less than intuition would serve. He found that the difference between the 10th and 90th percentile of speed score amounted to approximately four fewer hits over 150 ground balls. Faster guys likely beat out more infield hits, while the plodders might hit the ball harder increasing the odds of finding a hole in the defense. It’s also possible that speed score is not the best measure of the wheels on a player.
With a career batting average on groundballs of .183, Kotchman has neither hit the ball hard enough to find holes nor possessed the speed to beat out enough infield hits. This year that figure is .227. Some suggested factors that could indicate harder hit ground balls this year could include an increased line drive percentage, off-season vision correction, and an improved walk-to-strikeout ratio. Without the benefit of HITf/x it is impossible to know if there is any validity to these assumptions, but it’s never wise to dismiss something entirely.
The concern over Kotchman’s ground ball rate might be overblown. Ground ball rates are based on balls in play and Kotchman is an excellent contact hitter. He currently boasts a strikeout rate of 9.4 percent (of total at-bats) versus the average qualified first baseman’s strikeout rate of 20.2 percent. If batted ball rates were adjusted for at-bats instead of balls in play, here is what the results would look like over 1,000 at-bats:
The raw difference in the number of at-bats ending in balls in the air is 5.5 percent, less than half the 12.9 percent difference based on ball-in-play. What this means is Kotchman’s excess grounders largely are replacing strikeouts, not flyballs. At his career rate, that’s about eighteen more hits per 1000 at-bats; with any possible sustained improvement, even more.
Kotchman still has a way to go before convincing most analysts that he is a league average hitter, though ZiPs projects him at a 745 OPS the rest of the way. His power is well-below average for the position, and while groundballs are less likely to go for extra bases, flyballs that don’t leave the yard are less likely to turn into hits. If Kotchman has a chance to be an average hitter, its likely with his current profile, because his already sub-standard power will only decline with age.