Nats’ post-season roster: The position players

The Nats have a really solid starting lineup, but they are facing a couple of big decisions here. First, how do they use Ryan Zimmerman now that he’s back from the disabled list with Asdrubal Cabrera now in place and no obvious opening on the roster. Second, which bench players should be included on the post-season roster.

First, some principles—sabermetric research has long demonstrated that you get better predictions of post-season performance from looking at least the last two seasons than from just focusing on this year’s statistics. Fortunately, there are now websites that use sabermetric models to come up with estimates of future performance. I’ll use the ones published by FanGraphs (which are averages of ZiPS and Steamer projections), though other projections are available and give roughly similar results. In contrast, most reporters and bloggers focus just on this season’s numbers. The current-season stats can be especially misleading for bench players, who may have only 100 to 200 plate appearances, making the data very noisy and unreliable for projecting.

Here’s the Nationals’ usual starting lineup, with FanGraphs projections of batting average, on-base percentage, slugging percentage, and weighted on-base percentage (wOBA) in parentheses:

• C – Wilson Ramos (.270/.314/.433/.326)
• 1B – Adam LaRoche (.252/.344/.444/.344)
• 2B – Asdrubal Cabrera (.264/.325/.420/.329)
• 3B – Anthony Rendon (.275/.344/.443/.346)
• SS – Ian Desmond (.262/.313/.428/.326)
• LF – Bryce Harper (.274/.354/.483/.365)
• CF – Denard Span (.284/.336/.391/.323)
• RF – Jayson Werth (.280/.372/.453/.364)

We’ll start the discussion of the bench with the two players who will definitely be on the post-season roster:

• LF/1B/3B/DH – Ryan Zimmerman (.278/.345/.463/.354)
• C – Jose Lobaton (.239/.308/.352/.296)

Lobaton, of course, is the required back-up catcher and there aren’t really any other options to consider there.

Turning to Zim, the first point I’d like to make is that after taking account of Zimmerman’s defensive deficiencies (weak throwing arm, and for at least the next 3 or 4 weeks, lack of speed as his hamstring continues to recover) the only case for replacing any of the regular starters would possibly be as a platoon starter against left-handed pitchers. Zimmerman’s offensive advantage relative to Rendon of .010 in wOBA, or .025 relative to Cabrera or .031 relative to Span clearly don’t make up for the cost in defense.

What about in a platoon role? Here are the possible platoon arrangements, ranked (in my opinion) from best to worst:

• Zim replaces LaRoche at 1B against lefties. LaRoche has had fairly large platoon splits the last couple of years (.280 wOBA vs. lefties and .383 vs. righties this season; .253 vs. lefties and .343 vs. righties last season). Because LaRoche doesn’t have much range at first, there’s probably not much defensive cost either, though LaRoche obviously has more experience in picking throws to first.
• Zim replaces Harper in LF against lefties. Harper’s numbers haven’t been hurt against lefties this season, though over his career he has a normal platoon split (.345 vs. lefties and .333 vs. righties this season; .314 vs. lefties and .373 vs. righties over his 3-year career). Of course, Harper has quite a bit more range and a cannon for an arm, so the defensive cost of substituting Zim would be substantial.
• Zim plays LF against lefties, with Harper moving to center and Span moving to the bench. This move would give you a little bit more in terms of offense, but at the cost of making the team worse defensively at two outfield positions, as well as replacing one of the best base runners with one of the worst. In my opinion, that’s not a good trade-off.
• Zim plays 3B against lefties, with Rendon moving to second and Cabrera to the bench. Again, this move makes the team worse defensively at two key infield positions and with an even smaller benefit in terms of offense, since Cabrera as a true switch hitter is essentially equally good from either side of the plate. His career wOBA is .326 vs. lefties and .328 vs. righties.

If I were managing the Nationals, I’d go with option # 1 and platoon Zimmerman with LaRoche at first. In my opinion, none of the other options offer any true benefit, with the defensive costs outweighing the offensive benefits. My fear is that Matt Williams, who doesn’t seem to like Harper much, will go with option # 2 and platoon Zim in left field and that Zim’s lack of range and/or arm will cost the team in a key game.

Now, let’s talk about the rest of the bench. As I discussed in the bullpen article, I think the Nats should go with an 8-man bullpen, which leaves three more bench players after Zimmerman and Lobaton. I see five candidates:

• 2B/SS – Danny Espinosa (.222/.284/.362/.286)
• 1B/2B/3B/LF/RF – Kevin Frandsen (.274/.315/.361/.301)
• LF/RF – Scott Hairston (.237/.282/.417/.306)
• LF/CF/RF – Nate Schierholtz (.239/.285/.399/.300)
• LF/CF/RF – Stephen Souza (.239/.309/.399/.314)

I think Espinosa’s defensive abilities and speed as a potential pinch runner make him a relatively easy pick. Also, his extreme platoon splits make him useful as a pinch hitter against left handers. Despite Schierholtz’s awful performance this season, he’s the only left-handed pinch hitting option. (What’s the matter, Mike Rizzo? You’re not doing your job!) Schierholtz hit pretty well in 2013 and is still 30 years old, so I’d go with him as a left-handed bat and defensive reserve for the outfield.

That leaves one slot. I’d argue that Souza is actually the best hitter of the three, and he’d probably be my choice in an unconstrained world. But I doubt the Nats will go with the rookie (if they were planning to, I think he’d be seeing quite a bit more playing time since his call up). So it comes down to Hairston vs. Frandsen. Frandsen’s been the better hitter this season, though frankly neither player has been good. Hairston’s big platoon differential is an advantage in a pinch hitting role where the manager can pick and choose the spots, and is the better option late in the inning if the team needs a home run. Frandsen, on the other hand, is the better choice if the Nats need a pinch hitter to lead off an inning and get someone on base. With Espinosa and Zimmerman available, Frandsen’s defensive versatility isn’t needed. It’s a very close call, but I’d probably go with Hairston (though my real preference is Souza).