I've only seen a little tape of Benson, so I can't really comment on his swing, but correcting swing mechanics is pretty tricky. Think of guys like Cody Johnson. Probably had as much power as anyone in the minors when he was in the Braves' system, but they could never iron out his swing.
I'll be a tad disappointed if it's Anderson, but I trust the scouts. Don't know where they are going to get bats. It's all well and good that they will load up on bats with the Latin American signings, but those kids are usually a year or two further away than June high school draft picks.