When will Brandon Belt play in the big leagues? To the San Francisco Giants, there are two available time slots for such an epic and much-awaited debut: Start of the season or during the season. There is no doubt, we will see Belt sometime soon, but fans just want to know when.
The Giants are notorious for seasoning their players low 'n slow in the minors. We saw it with pretty much the entire pitching staff they have now, and we saw it more recently with Buster Posey. You can't rush these things. The Giants want their players to stay in the minors where they can get regular at-bats and learn the game on a consistent playing level. Then when they're ready, they're professionals.
It's a proven method the Giants use because it works. That's why they're World Champions, because they know how to use their farm system and brew players for success.