According to earlier reports, he does...he's packed on weight since then, but I remember the upright running style being a complaint about one Adrian Peterson, and I seem to recall him working out pretty well...
"Durability. It is the biggest question some talent evaluators have concerning a big back reminiscent of Hall of Famer Eric Dickerson. Peterson runs so upright and hard that 'he might make himself more of a target even to linebackers who will wind up doing people's taxes for a living,' NFLDraftScout.com senior analyst Rob Rang says.
Rang says some teams will red-flag Peterson.
'The big knock on him is the durability issue," Minnesota Vikings vice president of player personnel Rick Spielman says. "Because he's a taller back; because he has an upright running style; because he runs 1,000 miles an hour. Is he going to hold up from a durability standpoint?'"
-USA Today, 4/20/2007
Every tall back and upright runner deals with the same questions, but eventually most end up figuring it all out. The coaches will have him running with a lower pad level in no time.