In the years following a noteworthy 2011 campaign, Desmond Jennings has seen declining performance both at the plate and on the basepaths, leaving many Rays fans wondering if the prospect once lauded as B.J. Upton's successor will ever live up to expectations in center field.
An injury-marred 2014 of hot and cold play did little to dissuade this perspective. At 28 years of age and with three years of team control remaining, where is Desmond Jennings's place in an outfield alongside the sensational defense of Kevin Kiermaier and up-and-coming prospect Steven Souza? Can he can rebound from 2014, or even show glimpses of his 2011 self?
Before we discuss what Desmond Jennings is not, we should first focus on what he is: a 3.3 WAR centerfielder in 2014, above-average for his position, and an excellent fielder. He has shown the ability to hit for power, and that continued last season with 32 extra base hits, including 10 HR. While his 15 stolen bases are his lowest season total since his ascension to the majors, it is safe to say that his lingering knee soreness he suffered when struck by a foul ball last July hampered his ability to be a basestealing threat for the remainder of the season. The "floor" for Jennings is likely what he showed in 2014, which still adds a lot of value to the Rays lineup.
The expectation for Desmond Jennings coming out of Durham was to be a leadoff threat; an on-base machine and base path menace much like Carl Crawford. Unfortunately, Jennings has not had the same sort of sustained success at the plate, and has seen a decline in his ability to hit for average and get on base after three seasons with the Rays (.244/.319/.377 over 542 PA in 2014, compared to .259/.356/.449 over 287 PA in 2011).
Jennings' two worst seasons in the majors came in 2012 and 2014 (.309 wOBA and .313 wOBA, respectively). The common denominator? Jennings struggled with knee injury in both of those seasons, spending significant time on the Disabled List. The psychological effect of playing day in and day out with a nagging injury cannot be understated, especially for a hitter who uses his speed to turn a few would-be outs into infield hits. If you're looking for better performance, perhaps the best recipe for a bounceback season in 2015 is to simply stay healthy for its duration.
When Jennings is injured, plate discipline could also be an issue. In 2012 Jennings was walking at a rate of 8.2%, and in 2014 a slightly better 8.7%, but Jennings' more successful seasons came with walk rates above 10%, compensating for his higher than standard propensity to strike out. Whether these lower walk rates were a result of a more aggressive approach, pressing, major league pitchers figuring him out, or a combination of these factors requires us to delve deeper.
Taking a look at his 2014 Pitchf/x Swing and Whiff Rate from Baseball Prospectus provides some insight:
We can see Jennings is offering significantly at pitches well below the zone and whiffing at them at an alarming rate. This is odd for a hitter who finds most success with pitches middle to middle-in. My initial suspicion is that DJ's zone expansion is a result of him pressing as a result of his decreased performance due to injury. Looking at his whiff rates before and after, the data seems to support this hypothesis (note that DJ's second half was much shorter due to injury):
Post-injury DJ appears to be swinging at pitches low and in much more frequently. To see if this had any affect on his play, I looked at his batting statistics pre- and post-injury. Oddly enough, DJ appeared to outperform his first half of the season (.236/.322/.375 pre-injury vs .260/.298/.387 post-injury) from a hitting standpoint. This seemed to disprove my notion that injury handcuffed him.
Looking further at his peripherals, Jennings' K% remained around 19%, while his BB% dropped from 10.9% to 5.1%. This would be in line with an expanded zone, and a much less patient approach at the plate. While injury did not seem to physically effect Jennings' ability to hit, mentally he may have been taking a more aggressive approach in the batter's box by going after more pitches.
This shift at the plate may have been working; unfortunately, an early exit to end the season derailed whatever rebound he had started.
If he continues this approach, it will be curious to see how it translates to the upcoming season. Steamer currently projects DJ to be good for .311 wOBA and 2.7 WAR in 2015, which would be in line with his 2014 numbers (of note, Steamer also projects him missing 16 games).
Jennings recently described his knee as "one hundred percent" and that he was "ready to play some baseball." His personal goal for 2015? "Injury free, that's what I'm going for." While a breakout year for the veteran centerfielder would certainly elevate the Rays' chances at postseason baseball, a season of minimal injury may provide the consistency Jennings' needs to rebound in 2015.