Making sense of Jacoby Ellsbury's post-injury struggles

A big part of the Yankees offense early in the season was the tag team of Jacoby Ellsbury and Brett Gardner at the top of the lineup. However, since returning to the lineup on July 8 after a knee injury, Ellsbury has been a massive liability in the leadoff spot. From his return to Sunday's game against Toronto, Ellsbury has put up a .191/.233/.345 batting line. The sudden plummet in his abilities comes in stark contrast to his production before his stint on the DL, when he was hitting .324/.412/.372.

The obvious answer is that he has been both a beneficiary and a victim of BABIP. Before his injury, Ellsbury's BABIP was .379. After his return, that number has dropped to .205. In both cases, his BABIP was at an extreme level, but outwardly blaming bad luck for his recent performance would be a pretty bad PR move, especially when looking at other possibilities.

Lost in Ellsbury's early season success was his extreme power outage at the plate. Before getting hurt, his isolated power was just .047, effectively making him a slightly luckier Ben Revere. After his DL trip, his ISO has jumped to .155, but has also coincided with a massive drop in BABIP. It turns out, the same thing happened last year, looking at his first and second half splits:

In 2014, Ellsbury spent a lot of the season hitting third in the lineup due to various injuries. It would stand to reason that with players like Carlos Beltran and Mark Teixeira hurt, he may have tried to pick up the slack, taking aim for the short porch in right field. It would also stand to reason that after his stint on the DL this year, he has tried to make up for lost time by trying to hit everything 500 feet. He certainly wouldn't be the first player to do so.

If this is indeed the case, Ellsbury's aggressiveness is misplaced. He has shown the ability to hit for power before, but since coming back from the DL and swinging at more bad pitches, Ellsbury's average exit velocity has dropped from 88.75 mph to 85.98 mph, according to Baseball Savant. Most hitters have to settle for a lower BABIP if they want a higher ISO, but the tradeoff shouldn't be this drastic.

Sports psychology is an extremely complex and controversial field. While I can only speculate, Ellsbury might be struggling because he is trying to do too much. Perhaps when he decides that he wants to hit for more power, assuming he is making a concerted effort to do so, he subconsciously decides to swing at more pitches. While this results in more doubles and home runs, it can also result in more weak grounders to the pitcher and more lazy pop ups.

Intuitively, both the "hit for power" approach and the "swing at more pitches" approach seem like more aggressive mentalities to have as a hitter. The bad news is that Ellsbury is probably having trouble separating these two approaches. The good news is that if he can try to add some pop in his bat without expanding the strike zone, he might emerge from this slump a better hitter. In 2009, at the age of 35, fellow ex-Boston outfielder Johnny Damon set career highs in both BB% and ISO at the same time by being selectively aggressive. There is no reason why Jacoby Ellsbury can't do the same. North of the border, Toronto has been on a tear since adding a superstar in Troy Tulowitzki to the top of the lineup. Now the Yankees need their superstar back in the leadoff spot.

*Unless stated otherwise, data is courtesy of FanGraphs.