As you might already know by now, Carlos Beltran has been pretty bad ever since he signed on with the Yankees. Last year he was mostly hurt and ineffective and so far he hasn't gotten things going in 2015. Since last year, Beltran has hit .227/.294/.390, which is just below league-average, and not exactly what the Yankees were (unwisely) expecting to get when they signed him to a three-year deal. He has another $30 million owed to him through 2016, so the team won't be cutting him loose anytime soon. Now, instead of getting rid of him, the Yankees need to platoon him.
Despite being a switch-hitter, Beltran didn't do much against lefties with a 50 wRC+ last year. He's not exactly righting the ship even after surgery, so if he can't get it done, the Yankees need to turn to someone else who can–and we saw just that on Tuesday night. Chris Young has gotten off to a colossal start to the year, hitting hitting .276/.344/.690 over 33 at-bats in the early goings, and he has a 118 wRC+ against southpaws. If the Yankees want to give their lineup a boost, they should give Young more at-bats and Beltran less by platooning the two. It would be easy to say that Young should be starting over Beltran, but as good as he has been, things will eventually even off for him. It's better to keep him in a role that you know he can find success with while still allowing Beltran a chance to figure things out against his "stronger" side.
The plan so far seems to be to sub in Young for Brett Gardner or Beltran, but the Yankees can't really afford to go without Gardner for a game when they don't have to. Sure, Gardner might be below league-average against lefties (barely), but you're also taking away what he best brings to the table–his glove. I'd take a Gardner–Ellsbury–Young outfield over a Young–Ellsbury–Beltran outfield any day of the week, I don't care who does what against which handed pitcher. Beltran doesn't really offer much on either side of the ball, so there's no reason to keep his bat or glove in the lineup. Instead, they have to keep Gardner in the game, if only for his defense.
Beltran is not that middle-of-the-order bat he used to be, so there's no reason to force his bat in the lineup anymore. It's clear that the Yankees are really banking on career numbers being more indicative of future performance than recent trends, since Mark Teixeira, Brian McCann, and Beltran bouncing back this year was a key part of the Yankees offseason plan. However, at a certain point you have to accept that a player isn't what they used to be in their prime and career numbers no longer portray an accurate representation of the player you have. After all, Carlos Beltran has a career 125 wRC+ against lefties, but who actually believes he's still that player? It's time to adjust expectations, accept reality, and start relying less on whatever Beltran might offer if the stars aline correctly and start looking at how they can maximize the roster they have right now.
Of course, things could turn around at some point. By June, Beltran could be hitting again and Young might be a DFA candidate. ZiPs projects both outfielders to produce about the same league-average offense over the remainder of the season, though Young will provide a full 1.0 WAR more than Beltran, thanks to his glove. However, right here, right now, the Yankees need to see what they have in front of them and start platooning Beltran and Young until something changes.