Questioning Dexter Fowler’s Defensive Improvement

With pitchers and catchers reporting soon, we just about have all the major free-agent signings wrapped up. It looks like Yovani Gallardo is about to sign with the Orioles, and there are rumors that Dexter Fowler could soon join him now that Baltimore has apparently decided to give up their first-round draft pick. With so many good outfielders available this winter, as the music stops, the available chairs for Fowler seem less desirable than we might have thought at the end of last season. Fowler’s defensive numbers have been pretty bad over the last few seasons, but his UZR figure was close to average in his only year with the Chicago Cubs. Determining change in skill from small sample size can be difficult, but it does not seem likely Fowler greatly improved his defense last season.

Defensive statistics are much-maligned outside of the analytic community, and even among those who use advanced statistics, there’s a degree of doubt regarding their utility. Much of the criticism stems from a misunderstanding about how to use defensive statistics given the larger sample size necessary to draw meaningful conclusions. Looking at three seasons worth of UZR can seem like going too far into the past, leading to rationalizations about short-term spikes in defensive numbers.

Over the last four seasons, Fowler has put up a UZR numbers in center field of -13.6, -1.7, -21.8, and last year’s -1.9 mark. Taken on the whole, it would be reasonable to conclude that Fowler is a below-average center fielder. It might be easy to look at the last three years, point to two that are pretty close to average, and call the -21.8 an outlier. This isn’t advisable, however, as doing so completely ignores a full year of data and merely cherrypicks the good seasons. The graph below shows two lines: yearly UZR for Fowler over the past five seasons, and a three-year average of UZR over the past five seasons, which is more representative of Fowler’s defense.

Using three years of data smooths Fowler’s numbers considerably. The inconsistency of the yearly numbers largely evaporates and places Fowler’s defense somewhere between six and 12 runs below average at center field over the past few years. That inconsistency carried over to his WAR numbers as well, as the graph below shows.

Instead of a 1.4 WAR season followed a 3.2 WAR season, we see a pair of 2.5 WAR seasons the last two years. Not surprising for the soon-to-be 30-year-old, ZiPS sees Fowler as a 2.4 WAR player heading into next season.

But what about the possibility that Fowler’s defensive improvements are real? It does happen. Jhonny Peralta made himself a much better shortstop later into his career — and improved positioning could have helped Fowler last season, as could getting out of the ballparks in Colorado and Houston. That narrative was getting pushed early last season and it does have some validity.

Fowler did play very shallow defense prior to his arrival in Chicago. As the piece linked in the previous paragraph noted, Joe Maddon instructed Fowler to play deeper, potentially preventing more extra-base hits, which could have led to the observed improvement in Fowler’s defensive numbers. Pushing the narrative further, we have a bit of a proxy for scouting with the Inside Edge numbers. Here is how Fowler performed last season:

Looking at these numbers we might reasonably believe that Fowler is an average defender. That is one way to look at things, but for the narrative of Fowler’s improved defense to be true, his numbers would need to have exhibited improvement over past years. The chart below shows Fowler’s Inside Edge numbers over the past four years.

Is there a discernible difference? Is there anything in there that tells us Fowler was demonstrably better than he was in prior years? It doesn’t look like it.

So if he didn’t get any better last year, that still leaves the possibility that maybe Fowler is not quite as bad on defense as we think. His numbers above seem to fall in the range of an average center fielder. Except, on their own, the numbers can be deceiving. Here is a Fowler comparison with another center fielder, Angel Pagan.

Nobody confuses the 34-year-old Pagan with an average center-fielder anymore, and the San Francisco Giants believed the same, signing Denard Span this offseason. Even if we assume Fowler is something close to an average center fielder, we still have to consider his arm, which has accounted for around a quarter of his runs below average on defense over the past four years. The Fans’ scouting report appears to agree, giving Fowler below-average scores both for his strength and accuracy.

Believing that Fowler made big gains on defense last season would require ignoring one other piece of data: Defensive Runs Saved. The graph below shows the yearly and three-year average for Fowlers DRS over the last five seasons.

While DRS also showed an improvement for Fowler in 2015, he merely went from awful to bad. The three-year averages show a fairly steady decline consistent with the aging process.

None of this is to say that Fowler is a bad player. He is an average to above-average player who play below-average defense in center field. That is incredibly valuable, and if the rumors of a two year, $20 million contract are true, any number of teams should jump at the opportunity even with the loss of a draft pick. Long term, there are probably concerns about Fowler’s ability to stick in center field, and his arm might make left field the only realistic possibility in the future. Right now, Fowler is a consistent offensive performer with a high on-base percentage who can still man center field, even if he is on the lower end of the spectrum among fellow center fielders. Fowler likely did not improve defensively last season, but it certainly looks like whichever team signs him will be getting a very good deal.