How Many Runs Won’t Wil Myers Save in Center Field?

According to Dennis Lin of the U-T San Diego, the San Diego Padres — despite rumors to the contrary — aren’t interested in flipping the recently acquired Wil Myers to the Phillies in exchange for Philadelphia left-hander Cole Hamels.

Writes Lin:

Indications from sources within the organization… are that the Padres intend on playing all three of their newest outfielders, including Myers. The early plan is for the 2013 American League Rookie of the Year to start in center field, flanked by fellow power-hitting right-handers Justin Upton and Matt Kemp.

The bold is mine and the bold is of some interest insofar as center field, with the exception of 51 innings in 2013, isn’t a position at which Wil Myers has spent much time as a major leaguer. He played it to a greater extent in the minors, making about two-thirds as many starts there as he did in right field while still a member of the Royals organization. But one also notes that minor-league defensive assignment aren’t necessarily excellent indicators of future major-league defensive prowess. Miguel Cabrera, for example — on something more intimate than just nodding terms with inertia even as a 20-year-old rookie — nevertheless made more minor-league starts at shortstop than any other position. Michael Morse made 95% of his nearly 500 minor-league starts at shortstop leading up to his 2005 major-league debut. His physique now isn’t identical to his physique then, but he’s still the same human — and that human wasn’t a good shortstop in 2005.

So we acknowledge, owing to Myers’ minor-leaguer experience there, that center field at least won’t be entirely foreign to him. But having some familiarty with a position and possessing the capacity to prevent runs there at a league-average rate — these aren’t identical propositions. Our interest is in understanding the effect on the Padres’ capacity to prevent runs of Myers playing center field for that team.

There are probably multiple ways to estimate Wil Myers’ ability to prevent runs in center field. I’ll consider two of them here. One is easy and one is more difficult. Or more involved, at least.

The first is easy because it’s a fixture of the calculation for WAR. Over a full season, a league-average center fielder receives a positional adjustment of +2.5 runs; a corner outfielder, of -7.5. As Dave Cameron noted when introducing WAR to this site’s readership back in 2008, that gap is derived empirically using historical UZR values. Typically, defenders who’ve moved from a corner-outfield spot to center field have prevented 10 fewer runs per 162 games following the transition. Conversely, center fielders who’ve moved to a corner have saved more than 10 runs. Again, on average.

I say that those positional adjustments were derived empirically, but they were also derived empirically almost 10 years ago now. A lot has happened in 10 years. Like more than half of the Fast and Furious movies, for example. And a lot has happened in baseball, too. Clubs, or at least some clubs, have more thoroughly embraced the idea that a player with a center-field profile can have success in a corner-outfield position. Carl Crawford and Brett Gardner have mostly happened since then, neither typical corner outfielder but both successful.

This leads us to the second way of estimating the numbers of runs Wil Myers’ might prevent as a center fielder: by finding other recent players who’ve transitioned between a corner-outfield spot and center field — and then calculating the difference in the runs they’ve prevented at each position.

The challenge of doing so, of course, is finding players who’ve recorded not only somewhat robust samples at each position (because UZR becomes reliable rather slowly), but also samples that occurred either simultaneously or, at least, within one season of each other — so that it’s essentially the same guy producing the numbers and not the 22-year-old version of him versus the slower, 34-year-old one.

With this in mind, I first identified those players who’d recorded more than 1000 innings at center field between 2012 and -14. This wasn’t a necessary constraint, per se, but useful as a starting point to narrow the sample of players. From that sample, I found every defender who’d Played at least 500 innings at corner outfield position in the season just before, during, or just after another season during which he recorded at least 500 innings in center field. I then selected, from that group, defenders who’d played no fewer than 1000 innings at both positions (corner and center field) within three-year span.

The results: 12 players (including two versions both of Brett Gardner and Shane Victorino) who met the necessary criteria.

Below is a table featuring those 12 players as corner outfielders. Year denotes the relevant seasons included in the sample. Inn denotes total innings played at the relevant position during the sample. UZR denotes the numbers of runs saved at the position relative to a league-average fielder. UZR150 denotes the numbers of runs saved relative to average per 150 games (or, 1350 innings).

And now as center fielders:

One sees immediately the extraordinary variance that can occur in just a thousand-inning sample — and thus the importance of combining all the relevant player-seasons together. Between 2012 and -13, for example, Shane Victorino saved 32 runs per season as a corner outfielder but -3 runs as a center fielder during roughly that same time period. That’s a substantial gap — much larger than the 10 or so runs suggested by WAR’s positional adjustment.

In the aggregate, however — with samples of over 20,000 each — the numbers appear quite reasonable. As a group the 12 players here (or 14, depending on how one cares to define it) have saved about 9 runs per every 150 games as corner outfielders while saving 0 runs while playing center field during the same basic timeframes within their respective careers. Those defenders, in other words, have saved nine fewer runs per 150 games as a group while playing center field than either left or right field.

This figure is remarkably similar to the one already present in the WAR calculation. One notes, as well, that the positional adjustment present in the WAR calculations accounts for 162 games, while we’ve prorated the defensive-run figures here to 150 games. Accounting for that difference brings the difference between the two even closer to the 10-run figure already extant in the WAR calculation.

Turning our attention to Myers, specifically, we find that he’s produced 0.4 UZR/150 in right field over the first 1279 innings of his major-league career at that position. He has been, in other words, almost a precisely league-average defender there. Given the calculations present here, one could reasonably expect him, as a center fielder, to concede nine more runs defensively in 2015 — should he, in fact, play that position for the Padres.