Playing in Fenway, where there is 32 feet to cover as a leftfielder, he's bound to throw a few guys out! Outfield assists is an overrated stat. Vlad doesn't get many outfield assists anymore, because people don't run on him. People take the extra base Manny whenever possible, so he gets more opportunties to throw guys out. He's done the job by throwing out 12 baserunners, but let's not put him in the defensive category of Vlad and Ichiro.
Honestly now, Rodriguez has all the tools and Manny hits. If we're talking a complete player, Rodriguez is it. And a complete player should win MVP over someone who just hits when the stats are comparable.