With first baseman Kevin Youkilis out for the the season, the Boston Red Sox have been giving Mike Lowell starts at first base. Lowell hasn’t hit well this season (.300 wOBA so far). However, it has only been a bit over 100 plate appearances, and ZiPS RoS projects him for a .335 over the rest of the season. That is a far cry from what Youkilis had been producing (.419 wOBA) or was projected by ZiPS to produce over the rest of the season (.399 wOBA). Assuming 200 PA over the rest of the season (leaving aside the relatively minor difference in PA given their likely batting order placement), the difference between Youkilis and Lowell over these last 50 games or so would be about 10-11 runs, or about one win. (Youkilis is also defensively superior at first base, although over 50 games it’s probably only a couple of runs.) With the Red Sox still not out of the hunt for the playoffs with less than a third of the season to go, the difference is significant.
Boston has been giving catcher Victor Martinez occasional starts at first, but recently signed former Blue Jay, Marlin, and Met first baseman Carlos Delgado to a minor league deal with hopes he can help the team soon. The underrated-in-his-prime Delgado was unsigned in the off-season and spent the first part of the season rehabbing from off-season hip surgery. He doesn’t have a ZiPS RoS projection given that he hasn’t played in the majors yet this season. Given his layoff and rehab issues, I think it’s fair to use his CHONE pre-season projection of .337 wOBA true talent (ZiPS projected .364 prior to the season), which, his poor defense at first base aside, would make him about as valuable offensively as Lowell over the rest of the season assuming he could start right away — about a win or more worse than Youkilis.
A wOBA in the mid-.330s for a first baseman is not very good. However, with two players like Lowell and Delgado, a platoon is a good idea (at the moment, I’m not sure what the Red Sox plan on doing). As I discussed earlier this year in a Book-inspired post, one can’t just apply observed splits to players, one has to regress them against league average, etc., to get a useful platoon skill estimate. In a different post, I actually used Delgado as an example. Delgado’s larger-than-average splits actually make him more useful in a platoon role than players with smaller splits. Based on his .337 CHONE projection, I estimated Delgado’s true talent versus right-handed pitchers to be .352 wOBA. There is less variation (and a smaller split) among right-handed hitters with regard to platoon skill, but Lowell’s estimated skill vs. LHP is about the same as Delgado’s versus RHP: .351 wOBA.
Over a full season (700 PA), a Lowell/Delgado platoon is worth between nine and ten runs more than either one of individually — one win. Over the remainder of the season, of course, it’s only worth about 3 runs more than either one of them individually. It isn’t much of a difference over the last 50 games relative to the loss of an underrated superstar like Youkilis, but with the Red Sox not completely out of it yet, platooning Delgado (if he is ready to play) with Lowell at first would be a smart move.