Aside from a last minute decision regarding whether Steven Matz of Sean Gilmartin will take the final spot, the Mets' NLDS roster has been finalized. Because of Juan Uribe’s injury, outfielder Kirk Nieuwenhuis received the final bench spot on the roster, becoming the sixth outfielder on the roster. While he has had a flair for the dramatic this year—the home run against Jonathan Papelbon, three dingers in one game at Citi Field—Nieuwenhuis doesn’t really make sense for a number of reasons.
Three of the four Dodgers' starters are left handed: Clayton Kershaw, Brett Anderson, and Alex Wood will likely be starting games 1, 3, 4, and 5 for the Dodgers. The Mets’ lineup already has a fair number of everyday lefties. Curtis Granderson, Lucas Duda, and Daniel Murphy will all, most likely, start in every game, regardless of the handedness of the starter. Now, Wood might wind up in the bullpen, which would put three lefties in the relief corps, along with J.P. Howell and Luis Avilan.
The problem is that, because of the Mets’ rookie outfielder Michael Conforto, Kirk wouldn’t be the first left-handed outfielder off the bench. If we’re talking pinch-hitting success, Kelly Johnson also has far more experience and far better results than Nieuwenhuis, who has .091/.189/.212 line when not starting a game. Johnson also has plenty of outfield experience, if not as much speed or range. You also don’t want Nieuwenhuis batting against a lefty in this series—he did not have a single hit off of one in 2015, albeit in only in 11 plate appearances.
He’s a good outfielder, but the Mets have lots of good outfielders. Perhaps he’s brought in at the end of a game, along with Juan Lagares, to boost the outfield defense when the Mets are winning, but that means that you’re pulling a far more capable hitter out of the lineup if the lead disappears. Plus, with Yoenis Cespedes and Lagares in a game late, Nieuwenhuis’s glove isn’t quite as necessary as it was pre-Cespedes.
So who could the Mets have added to the roster that would have provided them with more value? There’s no slam dunk answer here, as just about every player the Mets left off the roster is either redundant due to positioning or has a serious flaw in their skill set. But I would advocate for Dilson Herrera getting the spot over Nieuwenhuis.
Herrera is a right-handed batter and would give the Mets an option to start over Daniel Murphy at second base if he’s really struggling against the Dodgers' left-handed starters. His value as a pinch-hitter against one of the starters is higher as well, due to his handedness. Herrera’s platoon splits are also not nearly as extreme as Nieuwenhuis’s are, allowing him to stay in a game against multiple pitchers if need be.
In less playing time this season, Herrera walked slightly more (11 to 10), stole as many bases (two), was caught stealing less (zero, twice for Nieuwenhuis), and hit almost as many home runs (three to four) as Nieuwenhuis has. In terms of batting, the only place that Nieuwenhuis had a clear advantage was in high-leverage situations, where he hit .217 to Herrera’s .091, but both of those splits came in tiny samples.
Herrera is a second basemen, a position that could be fielded by Murphy, Wilmer Flores, and Johnson. Does this team really need a fourth second basemen? No, but all of those other players shift around the diamond, so it isn’t as if he is backing up a player that doesn’t play elsewhere. Is it ideal? No, but it is no less redundant than carrying Nieuwenhuis as the sixth outfielder—seventh if you include Johnson. And, since he is taking Uribe’s spot on the roster, it makes sense to mention that Uribe also plays second base, so the team had designs on having another right-handed infielder on the roster.
If the Mets were playing a predominantly right-handed starting staff, this would be an entirely different conversation. If the Mets hadn't traded for Yoenis Cespedes, it would also not be as cut and dry. But given the team as it is constructed, and given the team they are playing in the first round of the playoffs, taking Nieuwenhuis over Herrera is the only position player roster decision that doesn't make much sense.