Tigers’ Ian Kinsler is hitting too many pop-ups

Undoubtedly, Ian Kinsler has been one of the most important players for the Detroit Tigers this season. His 116 wRC+ is the sixth-highest on the team, but it comes just slightly below the third-best total of 121 wRC+. His 4.1 fWAR leads all Tigers, and ranks top-five among second baseman and top 20 among all position players. Kinsler is having another great all-around season and has been an important spark at the top of the batting order.

But while Kinsler’s season-long numbers remain sharp, they slightly mask a troubling trend. To start the season, Kinsler was on fire. He hit 11 home runs within the first two months, which matched his total from 2015. His .315 average, .364 on-base percentage, and 141 wRC+ were sure to regress, but the start was encouraging nonetheless. The next two months represented a sharp drop-off almost everywhere, with most key numbers decreasing except for his walk rate.

The hope was that Kinsler would reverse this trend and begin to move back in the right direction, but the progression has continued to be downward. In 19 games so far in August, Kinsler is struggling to hit for both average and power. His on-base percentage only remains manageable because of a 9.6 percent walk rate. At this point, his overall 2016 numbers are being completely buoyed by his first few months.

He's probably getting a little unlucky

A couple of months ago, I dug into Kinsler's ability to drive the ball upward with authority, surging his home run total and other power numbers. I utilized Statcast data to observe how Kinsler was hitting the ball at an optimal angle more frequently and how he was generating a quality exit velocity while doing so. These same numbers tell an interesting story a few months later.

While the batted-ball science is still young, it has found that hitters are generally most successful when hitting the ball between 10 and 35 degrees and recording an exit velocity of at least 95 miles per hour. In April and May, 17 percent of Kinsler’s batted balls met this criteria. In June and July, this number jumped up to 23 percent, and it has settled to 21 percent in August. Meanwhile, Kinsler’s exit velocity has actually risen on balls hit between within this middle range (between 10 and 35 degrees) over the course of the season, averaging 89.9 mph in April and May, 90.3 mph in June and July, and 91.7 mph in August.

The above chart lists Kinsler's results on batted balls hit in the middle range with exit velocities 95 mph and higher. To be clear, this is a fairly small sample size; as mentioned above, only around 20 percent of Kinsler’s batted balls end up in this range, so the percentages should be observed accordingly. Still, the trend is a bit puzzling. Kinsler is hitting the ball more frequently in the productive range of launch angles than he was to start the year, while also hitting the ball harder. He just has not gotten the results to show for it. These numbers should correct themselves in time, but even so, they only represent part of the problem.

The bigger issue

August has been distinctly different for Kinsler in terms of how the ball is coming off his bat. After hitting over a third of his batted balls at launch angles below 10 degrees in the first four months, he has done so at only 19 percent in August. Correspondingly, his rate for batted balls above 35 degrees has increased from around 20 percent to 35 percent in August. In plain English, Kinsler has replaced ground balls with high fly balls and pop-ups.

If Kinsler were replacing ground balls with shots in the middle range, the results would be much more favorable. But replacing ground balls -- an area where Kinsler has recorded a .339 batting average this season -- with pop-ups is an awful trade-off. Most batted balls with launch angles above 35 degrees are going to be outs (Kinsler is hitting .123 on them), so hitting them with more frequency will surely have a negative effect.

Some of the numbers should work themselves out in Kinsler’s favor, as his average exit velocity is higher on line drives and fly balls in August that it has been for the rest of the season. However, the pop-ups are still a big concern. Until he reduces this rate to his early season numbers, his average and power will both suffer. If he can find a way to maintain the velocity he is generating on his swing and hit the ball at a slightly better angle, these outs will turn into doubles and homers. He may not get back to a .315 average and 141 wRC+, but he will be able to escape his August slump.