I don't thinks he's bad in the OF. Yeah, he definitely takes some aggressive routes, which will pay off when it works, and maximize the damage when it doesn't. So, you take the good with the bad there. And, he does have a decent arm. That's only half his contribution, though.
He doesn't do enough with the stick to play COF for a championship caliber team, IMO. His bat is better suited for CF, but he doesn't have the range play there. Offensively, he's replacement level, which should come as no surprise because that is what he is, a replacement. As a Sox fan, all I can hope is that his flashes of brilliance this year are enough to make Yankee management think he's a long term solution. I'd rather our pitchers have to face him than a Carlos Lee or Jason Bay type any day of the week.