From LoHud:
Cashman said it was Joe Girardi’s decision to send Molina, and he indicated that the veteran is still very much in contention for the backup catcher role. "He was brought in not to be an organizational catcher," Cashman said. "He was brought in to be an insurance policy, much like a (Ronnie) Belliard, much like some of those other guys. He’s also competing for the spot too."
Here's my take: the Yankees have nothing to gain, and a little to lose, by starting Jesus Montero on the 25 man roster. By sending Montero to AAA, you get three big advantages:
Delay his arbitration clock. If the Yankees have proven anything in the last few years, it's that they do have a budget. I wouldn't say keep Montero in AAA if he was needed, but so long as the need isn't great, cost control is a factor.
Give him more time behind the plate. When I've seen him this spring, Montero has looked better than I expected. But that doesn't mean he's been good. Another 50+ games working with pitchers, coordinating the defense, and dueling with baserunners will do him good.
Bring him up hot. It's a sign of unrealistic expectations when you're disappointed by 36 Spring Training at-bats, but for a hitter compared to Manny and Miggy, unrealistic expectations are par for the course. Don't let those idiot sports radio mouthbreathers destroy Jesus' fan support by letting him hit .200 in April in the Bronx. Call him up when he's seeing pitches well and feeling confident.