I don't think Peterson is getting enough love in this debate. We're still talking about a guy that has a dominant skill set as a runner. Now he has an offensive coordinator with a decorated history of getting the most out of RBs statistically, especially when they are talented like AP. Norv has already stated he'd like to get Peterson out in space more, and I think we can expect a career high in receptions given the lack of depth on the roster (I wouldn't expect a meaningful draft selection to be used on a 3rd down rookie) and the fact that Norv tends to leave his RB1 out there in passing situations.
The other two players are not without their warts, though the extent to which the issues will affect them is debatable. McCoy had a dominant year, but amassed 391 touches between the regular season and playoffs. McCoy is no old man, but that is an incredibly hefty workload and it wouldn't be unreasonable to fear overuse affecting him this season. As for Charles, as someone already mentioned, he's lost a lot of what was a dominant offensive line for him last season, which must be a concern going forward if those pieces aren't replaced.
I'm not saying that Peterson doesn't have his issues as well, but I don't think this is as much of a slam dunk as some posters have mentioned, especially in PPR leagues.