It's not only the average man, it's everything. Average, slugging, OBP, stolen bases. What made Hanley so good was his standing as a legitimate five-tool threat. That overcame his always-lousy D at SS. Now his power may have somewhat come back at Fenway, but that doesn't mean getting him while getting into another albatross contract would have made sense.
Also, just to drive the point home, Hanley's home/away numbers in 2011-12:
2011: Home/away OPS: .679/.730
2012: Home/away OPS: .882/.614
While last year he hit moderately better on the road than at home, he's hit very well at home this year, and now can't hit on the road. The problems are in his head, and those are the hardest to fix.