Garcia can chill out in the minors. He's rocking a .375 BABIP. That isnt going to sustain itself over the course of a long season. He can use a year down there to physically mature.
Castro can play for a bit. If he plays like he did this season, he's a trade piece at the deadline.
Garcia seems ready defensively. In any event 1B seems like the big hole offensively. Especially with light hitters at 3B, RF and C.