While he doesn't have the pedigree of a .300 hitter, he should be able to bring himself to hit closer to league average as he gets more comfortable. The thing that will always plague him is striking out too much and last season was certainly a case of that with a 34.3 K%. However, he does at least draw some walks and should be able to slightly lower that K-rate over time with more coaching. But, regardless, it will hurt his ability to ever be a solid producer in batting average.
But, that power! Wow. When inspecting his power numbers, you might think his HR/FB rate of 22.9% would be unsustainable since it's way above league average but that's actually lower than his past minor league history which was usually 26.5% or above. He's just got unreal power which seems to be very legit as his minor league numbers showed and prospect reports mentioned:
"The scariest thing is imagining if he’s able to build off his Jupiter performance. He struck out only a couple percentage points above league average for FSL (19%), while walking over 5% more (8.2%). His BB/K improving to that territory, we’re now talking about a .396 wOBA and ~5.7 WAR player. His power improves to 45 HRs on top of that? We’re now talking about one of the greatest hitters playing at the major league level, with a .423 wOBA and 7+ WAR."So, the ceiling is certainly high for him and expecting 30-40 HR from him in 2011 is entirely logical. To go with that, he'll knock in a ton of RBIs and has enough speed to snatch a few bases and score some runs. The only question mark from a roto-league perspective is about his batting average but his other skills will certainly be good enough to offset that.
All in all, it reminds me very much of the Carlos Gonzalez situation from last year where he was a sleeper but started to lose that tag as the hype grew in the preseason. Stanton's a player being drafted after the 10th round in 12-team leagues but he's got first round talent and may just deliver on that this year. I'd invest highly in him and try to reach for him before somebody else does.