Maybe Hollings shouldn't take too bad a hit for the botched exchange/fumble, but he definitely got away with another fumble that wasn't called by the refs (it was pretty clear on replay--WHEW!!). Bottom line, as stated earlier in this thread by a couple of people, is that Hollings doesn't have much experience and isn't proving any more or less durable than DD. The guy has 134 yards rushing in his whole career.
Right NOW, in my view, Wells is a better back. BUT, it's not that simple. They both have a career 2.9 rushing average. Hollings is faster and a better receiver. Wells is stronger and is a better blocker. They provide different things for different situations.
Come to think of it, Wells has practiced as a backup fullback when Norris and Baxter were hurt. Why couldn't we get both Wells and Hollings on the field at the same time?