A Mark Trumbo Platoon or: How I Learned to Stop Worrying and Love Ender’s Game

The D-backs have recently stated that they’re after an outfielder and starting pitching this winter (that sounds familiar). But if no outfielder is brought into the fold and injuries aren’t a problem, the D-backs would enter spring training with a five-man outfield of players they’ve already used this season. A.J. Pollock would lead the pack, almost certainly starting every day in center. David Peralta could get the lion’s share of starts in right, sitting occasionally in favor of Cody Ross against lefties. Mark Trumbo would be the expected everyday starter in left field, with Ender Inciarte a great left-handed complement to the right-handed Pollock and Trumbo.

But should that be the case? Take a look at these two batting lines from this season, and try to guess whose they are:

Give up? It was actually something of a trick question: both lines are from the same player. The first row shows stats against southpaws, while the second is against righties. And yes, he’s had less than 250 PA this season, so drawing broad conclusions isn’t exactly fair. But the difference is so big that it may nonetheless be meaningful. 200 slugging points is like the difference between Paul Goldschmidt and Didi Gregorius: pretty significant. Some teams don’t have any players who put up a wRC+ of as high as 141 (on the D-backs, Goldy is the only one who has done that in a large sample), and 64 wRC+ is atrocious, the kind of rate you see for some backup catchers.

You guessed correctly from the title that the player in question is Mark Trumbo. And it’s a little unfair to pick on him for 2014 performance. But this platoon split isn’t exactly a new thing, especially in the slugging department, and it’s made his effective platoon split higher than a difference in batting averages would indicate. Last year, Trumbo created runs at a well above average rate against lefties (154 wRC+), but lagged below league average against righties (90 wRC+). And while there was a 42 point drop in batting average, the real difference was that one skill that the D-backs seemed to prize above every other important thing: power. Last year, Trumbo had a .599 slugging percentage against LHP, compared to just .402 SLG against RHP.

That’s a pretty big gap. Maybe Trumbo won’t have that big a platoon split going forward, but he’s going to have one, and it’s going to make a difference in the home runs department. In the last two years combined, Trumbo has hit bombs about once every 14 PA against lefties, but once just every 26 PA against RHP:

Position Wars: A New Hope

Ender Inciarte was almost lost to the organization completely not too long ago. In the December 2012 Rule 5 draft, Inciarte was selected from the D-backs by the hapless Phillies. He was returned to the D-backs organization in early April after the Phillies used a waiver claim to obtain a similar but more advanced outfielder (Ezequiel Carrera). Inciarte had only played Single-A ball at that point, and the fact that he was selected at all was some indication that at least one team viewed Inciarte as a fifth outfielder.

It’s possible that that’s who the D-backs have thought he’d be, too. Slated to start the season with his first taste of Triple-A, it’s probably fair to say that Inciarte was somewhere between 7th and 10th on the outfield depth chart before the season began. Despite that, Inciarte has amassed a half-season’s worth of playing time (297 PA) through August 21.

Inciarte has been nothing special at the plate: 26% below average at creating runs (74 wRC+). He’s a light hitter with a batting average right around league average but a slugging percentage that is quite low (.335 SLG). But in half a year’s time, Inciarte has amassed 1.5 wins above replacement per the FanGraphs formula (1.8 per Baseball-Reference).

Defense is the reason. In a small amount of time in left field (70.2 innings), Inciarte has had a stunning 50.8 UZR/150, which is ridiculously high (like saying he’s worth 5 and a half wins just with his defense), but obviously due at least in some part to random variation. In a still-small but much more reliable sample in center field (544.1 innings), Inciarte has had a 22.7 UZR/150. That’s still excellent, considering that in center, Inciarte is judged against his peers, many of whom are quite good out there (including A.J. Pollock).

Whether or not the defensive statistics represent true talent levels is a legitimate question, but both UZR (Ultimate Zone Rating) and DRS (Defensive Runs Saved) agree that Inciarte’s defense has been worth about 14 runs (above average, as opposed to above replacement). Throw that together with his underwhelming hitting, and you get a player who’s been worth a win and a half above replacement. Kirk Gibson has gotten him more starts against RHP than the average player would get, so we can’t just double his 1.5 WAR to 3.0 in guessing what he might be worth in a full season. But 2.5 WAR seems like a reasonable guess. 2.5 WAR is not all-star level, but it’s also a player that even championship-caliber teams would think twice before replacing.

That’s all a long way of saying: Ender Inciarte is actually a pretty good player. As a starting outfielder, he’d be a pretty good player. He really is like a “lite” version of last year’s Gerardo Parra, and it’s a testament to just how great a year Parra had in 2013 that a lite version could still be solidly starter-worthy.

Ender Inciarte as a Left Fielder

Left field can often be the last position that General Managers worry about when constructing a roster. No special skill set is required there; to succeed, you don’t necessarily need the range of a center fielder, the reaction time of an infielder, or the throwing arm which is generally more useful in right field (both RFs and LFs can be called on to throw to second base and home, but LFs are rarely called on to throw to first base, whereas RFs can keep base runners from advancing to third).

Individual runs saved as measured by UZR or DRS are equal at every defensive position; that’s just how they’re measured. Defensive talent may not translate to runs saved as easily in left field; last season just 6084 total plays were made by left fielders. Some of those were “out of zone” for LFs (2860), but LFs had about 3,558 chances for in-zone plays. That’s considerably less than the 6,668 chances for in-zone plays for center fielders, although the way “zone” is defined is also representative of the ranges expected of fielders at the two positions (the discrepancy between “out of zone” plays by fielders at the two positions is not nearly as high).

But it’s not like defense doesn’t matter in left field — it’s just that the difference between a good fielder and a bad one isn’t quite as high as it might be elsewhere.

Advanced fielding statistics are good measures of what has actually happened on the field (with the possible exception of outfield arm statistics, which rely in part on inferences). They aren’t necessarily indicative of talent levels; the usual rule of thumb is that it takes three years’ worth of defensive statistics before one can start to draw reliable inferences about a fielder’s true talent level.

So I’m not sure just how much of an impact Ender Inciarte’s defense could have in left field as compared to Mark Trumbo. But I think it’s fair to expect that Inciarte can be at least as good a left fielder as he’s been a center fielder; he may not get as many chances, but his range will outpace the average fielder much more in left, and like in-betweener Gerardo Parra before him, Inciarte appears to have an outstanding throwing arm, which could have a slightly higher impact in left field than in center.

Over a full season, I think it’s fair to guess that Inciarte could be worth 30 or more runs saved in left field as compared to the average left fielder. Because the bar is so low, Trumbo’s lumbering efforts out there aren’t terrible when compared to his peers (about -9 UZR/150 for the outfield). We can guess that as compared to Trumbo, Inciarte could be worth an extra 40 runs saved in left field, which is the equivalent of 4.5 wins or so.

An Inciarte/Trumbo Platoon Could be Incredible

All other things being equal, Trumbo would make up a big chunk of that 4.5 wins difference with his hitting. But as we saw above, there’s a predictable way in which his hitting is sometimes subpar. Unfortunately for him, any platoon situation would put him on the “weak” side (generally, only 40% of MLB plate appearances come against lefties). But that’s the trick: even though the difference in the two players’ defense should hold regardless of who takes the mound in the other half-innings, the difference in the two players’ hitting capabilities is not.

Ender Inciarte has been nothing special at the plate so far in his major league career, but has been better against RHP (78 wRC+) than LHP (67 wRC+). He’s not as good as Trumbo is likely to be against RHP, surely, despite Trumbo’s 64 wRC+ against RHP so far this season. In a vacuum, maybe with Trumbo feeling healthier at the outset of 2015, he could return to his 2013 level against RHP: 90 wRC+.

It’s possible that Inciarte could improve with a chance to develop at the major league level. Against RHP, the left-handed Inciarte could end up in the low 80s in terms of wRC+. But let’s assume that Inciarte will hug the 75 wRC+ range against RHP.

In a half season’s worth of playing time against RHP, the difference in runs created between a 75 wRC+ and a 90 wRC+ about 6 runs, or just over a half win. That’s pretty significant. But in that same half season, Inciarte could be worth 20 more runs saved on the defensive side. In a half season against just RHP, Inciarte could be worth almost a win and a half more in left field than Trumbo.

Of course, there is no such thing as a perfect platoon. Regardless of whether the D-backs embraced a time share between the two players and started Trumbo against all LHP but Inciarte against RHP, there’d be some overlap. But here are my estimates, based on Oliver projections and our own math above, for what the team might get out of left field. I’m switching from wRC+, a rate stat, to RC, the counting stat it uses to compare hitters. “Runs Created” are runs, just like UZR measures runs. But note that Runs Created isn’t compared to a replacement level (which is what WAR does) or an average level (what UZR does). Full disclosure: I’m making some guesses here, but I’m trying to err on the side disfavoring my conclusion. Also note that there is a hefty positional adjustment for left field in terms of WAR.

Trumbo only: 1.4 WAR (60 RC, -10 UZR)

Inciarte only: 2.5 WAR (50 wRC+, 30 UZR)

Trumbo against LHP (40% of season): 1 WAR (30 RC, -4 UZR)

Inciarte against RHP (60% of season): 1.7 WAR (36 RC, 18 UZR)

The sum of the last two lines is greater than either of the first two. It’s actually not a huge advantage on Inciarte alone. But in smaller does (against LHP), Trumbo is the better player, and that makes a difference.

Switching gears to a more editorial voice here: I don’t think Trumbo is a very good player, at least as an outfielder. He’d make a damn fine DH. But this post isn’t about that. It’s about how, regardless of what you think about Trumbo’s skills or his profile in terms of winning games, we can and probably should all agree that a hefty chunk of Trumbo’s goodness can be juiced out of him in starts (and pinch hitting opportunities) against lefties. Maybe Inciarte is actually the better player overall, and even against lefties — that is what the very slight difference between Inciarte only and the proposed platoon strongly suggests. But Inciarte is absolutely the better player against RHP. With the D-backs not having much of a stake in Trumbo’s future (just two more seasons), and with a highly capable fill-in available, it’s time to start limiting Trumbo’s starts against right-handed starters.