From the Baseball Prospectus 2008 Annual:
...just might be the next big thing. Going into the season, he was a raw athlete who was loaded with athletic gifts but offered little in the way of baseball skills, but one could argue that no player in baseball took a larger step forward in 2007. He projects as a leadoff man who can hit 20 home runs, steal 50 bags, reach base at a .400 or so clip, and play an outstanding center. If you start talking about him now, you'll look smart, because chances are good that he'll be on everyone's lips a year from now.
Until his eventual callup, it was rather impossible to separate Desmond Jennings
from Carl Crawford
comparisons. The 2010 annual even stated, “The Carl Crawford
comparisons are inevitable," while going on to say that Jennings has a better approach at the plate. His 2011 player description wondered if Jennings would make a Buster Posey
like impact for the Rays that season (he actually did, after being recalled in August). His 2012 preview hinted at how pitchers found a way to get Jennings to expand his zone upward and then off the plate and how he struggled over the final weeks of the 2011.
Fast forward two years and Jennings more closely resembles the Carl Crawford
that played for Boston than he does the one that flourished in Tampa Bay and the former highly-regarded sure thing prospect is having a second consecutive disappointing season at age-26. In two full seasons of baseball, he has yet to approach 20 home runs or 50 steals, and has not been anywhere near a .400 on base percentage. Is it time to write him off as a bust as he enters his age-27 season?
There are some out there that believe age-27 is the season to target players. I also feel those people still believe the Earth is flat and we never landed on the moon because it is a theory
based on junk science. We know from 2005 research by Nate Silver that center fielders age more quickly
than the overall player pool and from Mitchel Lichtman that ages 26-28 are indeed the peak years
for player performance. Jennings has just completed his first season of his peak years but has another two to go. What he has done this season is not predictive of what is to come, but it should help level set what may happen over the next two seasons.
Simply put, this is a player with flaws and those 20-homer, 50-steal, .400 OBP expectations need to be adjusted.
In September 2011, pitchers limited Jennings to a .160/.258/.245 slash line by feeding him a hefty diet of high fastballs and sweeping breaking balls. In fact, 78 percent of the pitches he saw that month were from that menu and he had just four extra-base hits in 120 plate appearances. That is a recipe that pitchers have stuck with over the past two seasons as Jennings continues to struggle with handling it.
Over the past two full seasons, 92 percent of the pitches Jennings has seen have been some variety of a fastball or a breaking pitch. Against the fastballs, Jennings has hit .273/.367/.467 with an 18 percent strikeout rate, a 12 percent walk rate, and a .313 batting average on balls in play. When pitchers make a mistake with a fastball, Jennings has the ability to make hard contact with it. It is the fastballs that get above his swing plane that he still has issues laying off.
Over the past two full seasons, Jennings has seen just over 2,700 fastballs (four-seam, two-seam, cutter) from all pitchers:
A batter cannot simply take high fastballs for strikes, otherwise opposing pitchers would stay up there all day long and pile up nice strikeout totals. It is an enticing pitch for batters to swing at because it is eye level, but that also means that the pitch gets on you quicker. Jennings has a rather level swing, as shown in the two animations below from September 2012 and 2013.
Note there is very little different in those swings, despite being a full year apart. He still uses an ever-so-slightly open stance to start and he holds his hands high as the pitcher starts his delivery. His hands are a bit lower in 2013 than they were last season, but not demonstrably much. He also seems to have moved a bit back off the plate this season, which is concerning given his issues with breaking balls away. The swing is conducive to line drives on pitches that are in the lower half of the strike zone, but it has not been productive against elevated fastballs, particularly from right-handed pitching.
Jennings has hit just .233 against right-handed pitching over the past two seasons. If we focus simply on fastballs in the upper half of the strike zone, that average falls to .215 as he swings 56 percent of the time at those pitches and has just a .233 BABIP with those. When righties switch to the breaking stuff, Jennings has hit just .219 off breaking balls from them with a .519 OPS.
Jennings has had a fair amount of success against left-handed pitching having hit .270/.355/.435 over the past two seasons while hitting .279/.380/.500 against elevated pitches from the port-siders.
Jennings plays above average defense and is still an excellent baserunner which makes it easy to put him in the lineup on a daily basis. Yet, it is obvious this is a flawed product when someone with the praise he has been given is jostled between the leadoff spot and the lower third of the lineup on a nightly basis depending on the handedness of the pitcher.
His overall 2012 slash line was .246/.314/.388 while his current 2013 is incredibly similar at .242/.322/.395. This is nearly 1,500 plate appearances of performance that comes in well below the expectations people had for him. He has made slightly more contact this season and is walking a bit more, but at a time when we look for growth in hitters heading into their peak years, we see someone flat-lining.
In 2012, Jennings went for $27 in AL Tout Wars, and went $2 cheaper this past season. Given what we’ve seen from him over the past two seasons and 1,500 plate appearances, any bid over $20 would be incredibly speculative. What he has done to date simply does not justify it.