The logical option would have been to sit Skip Schumaker and slide Yasiel Puig over to center field, with Van Slyke playing right field. Instead, Schumaker is starting in center field batting seventh.
Schumaker vs. LHP (2013)
14-for-55 (.255), .305 OBP, .327 SLG, 3 BB, 13 K
Van Slyke vs. LHP (2013)
15-for-64 (.234), .342 OBP, .422 SLG, 3 HR, 11 BB, 17 K
While Van Slyke isn't exactly mashing against lefties, he provides much more value against them. However, he might not provide as much an offensive upgrade over Schumaker that Mattingly wants to risk hurting the defense. Schumaker isn't the next Mike Trout in center field, but Puig is even worse.
According to defensive metrics (which aren't always the best indicator of ones defense), Van Slyke is actually a solid defender in right field (-1 defensive runs saved, 1.4 UZR/150), granted, in limited time (80 1/3 innings). Schumaker, albeit playing a tougher position, is a -3 DRS and -12.8 UZR/150 guy in 167 center field innings. Puig, in 55 innings in center, was pretty atrocious: 0 DRS, -36.3 UZR/150. It's a small sample size, but he's absolutely best suited to play right field.
Carl Crawford could handle center field. And keeping Puig in right field might be the best part about this decision. Seeing as guys like Van Slyke and Dee Gordon were getting reps in center field before the playoffs, it's safe to say the Dodgers don't really want Puig playing center field -- especially in the postseason.
With Zack Greinke on the hill, it'd be nice to have the best defense out there for him. If nothing else, Van Slyke can pinch-hit later in the game, if necessary.
Here's hoping for more of the same from the Dodgers today.
Van Slyke: Mad Peruvian Media, Flickr
Schumaker: Dustin Nosler, Feelin' Kinda Blue