That’s the question being asked many fans, analysts, talking heads, and sports journalists across the country. It’s hard to blame them. At age-36, Jeter put up his most disappointing season to date, posting career lows in OBP, SLG, wOBA, wRAA, WAR, HR, ISO, EqA, OPS, and just about every other “acronym” stat that comes to mind.
To many, Jeter’s performance regression came as quite a shock. After all, just one season prior, Jeter looked like a man on top of his game, producing an MVP quality season. Looking like a renewed force determined to fight the effects of aging, many figured Jeter would continue to play at a high level for the foreseeable future. That didn’t happen. Instead, Jeter struggled in 2010, and produced a season on par with what we’d expect out of Marco Scutaro. No offense to Scutaro, but I don’t think anyone will confuse him with the future Hall of Famer.
Over the last few months, there have been more than a few hypotheses floated as to why Jeter’s performance regressed so dramatically. I thought I’d take a look at a few of these in determining whether it’s reasonable to expect Jeter to return to form in 2011.
The Swing Hypothesis
A couple of weeks ago, Ben Shpigel of the New York Times wrote a piece about Derek Jeter’s work with Yankee hitting coach, Kevin Long, to retool his swing for the upcoming season. Here’s what he had to say:
“If he hits .320 last year, I’m not changing one thing,” Long said in the bar area. “In Derek’s case, he hit an all-time low, and this is something he felt the need to do. It’s hard for me as a hitting coach to say that I did a good job with Jeet last year. I look at it like I failed him. He’s on a mission, like he said, and so am I to get him back to where he needs to be.”
The only thing that really concerns Long is Jeter’s batting average, which plummeted 64 points last season to .270. The drops in home runs and slugging percentage, the spike in strikeouts, Long considers normal, or at least not abnormal.
If by eliminating his stride, Jeter, a .314 career hitter, can restore, say, 30 points to his average, his on-base percentage, an integral facet for a top-of-the-order hitter, will improve, too. Everything else is secondary.
While many of us, especially those statistically inclined, might consider the “mechanical issue” to be a convenient excuse for the obvious (age-related regression), it appears there might be some credence to this hypothesis. After reviewing Jeter’s batted ball statistics, it becomes increasingly clear that something was different in the way he performed in comparison to years past.
Throughout his career, Jeter has been known as a heavy ground ball hitter. Between 2002 and 2009 (comprehensive batted ball data doesn’t exist prior to 2002), Jeter produced a groundball rate (GB%) of 55.6%. In 2010, his GB% skyrocketed to a career high 65.7%. So what happened?
| Year | GB% | FB% | LD% |
| 2002-2009 | 55.6% | 23.4% | 20.7% |
| 2010 | 65.7% | 18.2% | 16.1% |
It’s tough to say exactly. After looking at all of the data, it appears that Jeter may have, in fact, altered his swing slightly, which caused him to hit the top part of the ball more often. Without video confirmation, I can’t say for sure whether this was actually the case. Still, the increase in ground balls along with a corresponding decrease in fly balls and line drives indicates that a mechanical flaw may have been partially to blame for his sub-par season.
The Age Hypothesis
I’m going to say something that may or may not shock you. Baseball players have a tendency to decline once they reach the age of 30. (Gasp!) While this might seem painfully obvious to some of you, it’s amazing how many people don’t understand (or refuse to believe) this simple concept. Despite seeing everyone one of our heroes eventually succumb to age-related decline, we, as fans, tend to ignore or discount the powerful effects of aging. We assume they’ll continue to perform at the same level, regardless of age, yet we’re surprised when they fail to meet our expectations. It’s irrational for us to think this way, but we do it anyway.
Last season, Derek Jeter turned 36 years old. While that’s by no means old in terms of the human life cycle, it’s pretty old in baseball terms. In terms of the shortstop position though, it’s downright ancient. Shortstop is considered to be a position where youth, agility, athleticism, and defensive prowess (not experience) are vital. Not surprisingly, it’s not a position were many players in their mid-to-late 30s can survive.
Since Jeter is about to enter his age-37 season, I thought it would be fun to do a little research to see how shortstops performed during their age-37 seasons. Along with a little help from Fangraphs and Baseball Reference’s amazing Play Index tool, I was able to do just that. For the purpose of this exercise, I used the following parameters:
- Each player must be in his age-37 season
- Each player must have accumulated enough plate appearances to qualify for the batting title
- Each player must have played at least 75% of his games at shortstop during his age-37 season
- The sample seasons would be limited to the modern era (1901-2010)
After plugging in these parameters into the Play Index, I found eleven shortstops fit this description. After sorting them by Rally WAR (rWAR), and then converting them to Fangraphs WAR (fWAR), here’s how the eleven shortstops performed:
- Honus Wagner (1911) – 7.5
- Ozzie Smith (1992) – 5.4
- Rabbit Maranville (1929) – 3.5
- Omar Vizquel (2004) – 2.9
- Maury Wills (1970) – 2.4
- Pee Wee Reese (1956) – 2.2
- Larry Bowa (1983) – 1.7
- Dave Bancroft (1928) – 1.7
- Bill Dahlen (1907) – 1.5
- Dave Concepcion (1985) – 0.9
- Luis Aparicio (1971) – (-0.3)
(For reference, Jeter produced 2.5 fWAR during his age-36 season.)
Needless to say, history has not been kind to 37 year old shortstops. Out of our eleven player sample, only four exceeded the 2.5 fWAR Jeter produced last season. Three of those players (Smith, Maranville, and Vizquel) were defensive wizards, while the other (Wagner) was a freak of nature who managed to produce 26.3 fWAR between the ages of 38 and 43—including a 9.3 fWAR during his age-38 season.
While Jeter is neither a defensive wizard nor a freak of nature (at least not like Honus Wagner), it’s not out of the question to project a 3-4 WAR season for him this season. Projecting anything higher would probably be irresponsible, but considering his recent performance history, there’s no reason to think he can’t produce at that level.
The Past Performance Hypothesis
For most people in or around the game, the most confusing aspect of Jeter’s disappointing performance was that it came just one season after he produced a bonafide MVP quality season. It blindsided nearly everyone. A big reason for that is due to something called the “Recency Effect,” which was described by Johan Keri last month in an article he wrote for Fangraphs.
“The Recency Effect is a phenomenon that can overpower even the savviest thinkers. We tend to place too much emphasis on an event that just recently occurred, and lose sight of the much longer string of events that immediately preceded it. If you eat a banana and you’re blowing chunks 10 minutes later, you might shy away from bananas in the future, even if you’ve eaten hundreds of them in the past without incident.”
Rather than assuming Jeter would regress back toward his statistical mean in 2010, many assumed that he would continue to play at his 2009 level—or at least reasonably close to it. Considering his age, performance indicators, and recent performance history (three year sample), those were incredibly unfair expectations.
So what kind of performance should we have reasonably expected from Jeter? Well, for starters, we probably should’ve expected a season much closer to the type of season he actually produced. Reviewing his last four seasons, using Fangraph’s WAR (fWAR) as our guide, we see that Jeter produced 3.5, 3.7, 7.1, and 2.5 fWAR respectively. Looking at this objectively, it becomes clear that Jeter’s MVP quality season (7.1 fWAR) was probably an outlier season. His performance in 2010 was merely regression back toward the mean (and probably a little further beyond it).
| Year | Batting(wRAA) | Replacement Value | Defense(UZR) | Positional Value | fWAR |
| 2007 | 22.3 | 23.8 | -17.9 | 6.8 | 3.5 |
| 2008 | 8.4 | 22.3 | -0.3 | 6.3 | 3.7 |
| 2009 | 36.6 | 23.9 | 6.4 | 5.9 | 7.1 |
| 2010 | -0.8 | 24.6 | -4.7 | 6.2 | 2.5 |
Now, that we’ve identified that 2009 was probably an outlier season, it’s important to know what caused this phenomenon. The above chart breaks down fWAR into its four primary components: batting (adjusted wRAA), replacement value, defense (UZR), and positional value. Since there’s only a very small variance in both replacement and positional values over our sample, we’re going to ignore those components. Instead, we’ll focus solely on defense and batting.
First, I want to focus on defense.* It has been well documented that Jeter’s defense has not performed well under the light of advanced defensive metrics like UZR. After several years of producing at a below average level, Jeter posted a positive UZR, +6.4, for the first time since 2002. Considering his past defensive struggles, most analysts figured this was a statistical anomaly caused by small sample size variance (UZR samples become valid after approximately 450 games), and predicted Jeter’s performance would regress back toward the mean in 2010. Like clockwork, this is what happened. In 2010, his UZR dropped to -4.7, which removed almost 1.1 WAR from his 2010 total (in comparison to 2009).
* Without getting into a stats vs. scouts debate, I’m going to make the executive decision (it is my article after all) to ignore the anecdotal and subjective scouting analysis in favor of the statistical analysis. Scouting analysis always has value. The reason I’m ignoring it in this case is because it’s not quantifiable.
Now, let’s take a look his offensive production. After reviewing Jeter’s weighted runs above average (wRAA) statistics from the fWAR chart I posted above, we see that he produced a difference of 37.4 wRAA between his 2009 and 2010 campaigns (36.6 vs. -0.8). Why did this happen? Well, there are a couple of reasons. One, Jeter produced an unusually low line drive rate (16.1% vs. a career 20.7%) in 2010. With the xBABIP for line drives being around .730, it shouldn’t come as any surprise that line drives are where hitters get the biggest bang for their buck. As a result, when a hitter sees a 20% decrease in his line drive rate, his batting average and OBP will likely take a massive hit as a result. In the case of Jeter’s 2010 season, this is precisely what happened.
Two, Jeter benefited from an unusually high HR/FB rate in 2009, which had a significant effect on his slugging percentage. His elevated 2009 HR/FB rate was likely caused by one of two things: (1) the slightly smaller dimensions at the new Yankee Stadium; or (2) luck. While Yankee Stadium’s smaller dimensions (particularly in left-center), may’ve had an affect on Jeter’s 2009 power surge, the fact his HR/FB rate regressed back to his performance baseline (~9%) shows that it probably wasn’t a major contributing factor.
| Year | HR/FB |
| 2007 | 9.3% |
| 2008 | 9.0% |
| 2009 | 14.6% |
| 2010 | 9.9% |
That leaves luck as the most viable explanation. Most people aren’t terribly fond of the “luck excuse,” but that’s mostly because they don’t understand it in terms of baseball and statistical terms. Allow me to explain. If you were to flip a coin 50 times, you could reasonably expect the coin to come up “heads” 25 times. Sometimes you get 25, others you get 22, and others you get 29. In most cases though, you’ll get results that are reasonably close to that expectation. Occasionally, you’ll do this experiment, and the coin will come up “heads” 35 times…or even 40 times. Does this mean we should expect this trend to continue? Of course not! Over repeated trials, we should expect this trend to regress back toward the mean. Essentially, this is what I (as well as other baseball writers) mean by luck. “Luck” is any outcome that falls far outside the expected range of results (i.e. true talent level). Since it’s unexpected, we shouldn’t assume the trend, whether favorable or unfavorable, will continue into the future. Eventually everything regresses back toward the mean.
For Jeter’s HR/FB rate, the luck explanation seems to fit. In this case, his luck could have been caused by simply hitting a fly ball in the right ballpark to the right spot at the right time, or benefitting from a friendly gust of wind that pushes the ball just over the fence. It happens. His 2009 power surge was an aberration, so we should not have been surprised to see his HR/FB rate (and therefore his home run total) to regress back to his true talent level.
In conclusion, I think it’s pretty safe to say that we probably won’t see Jeter post another 7 WAR season. He’s too old, and quite frankly, not talented enough anymore (in the true talent sense) to pull that off again. Still, I’d be very surprised if Jeter didn’t see at least a small bounce back in his performance in 2011. If Jeter’s swing adjustments prove to be fruitful, he’ll probably post higher batting average, OBP, and home run totals. As a result, he could add as much as an additional 1.0-1.5 fWAR in value. I’m predicting 3.2 fWAR for Jeter in 2011.
Knowing what we know about Jeter, I’d never suggest betting against him.