Obviously Ware is at about the lowest weight guys CAN be successful at DE. Playing against him in a big way is that he hasn't learned that position at the pro-level. How many of these guys started as 3-4 OLBs then moved to DE? A guy like Osi who is an obvious comparison took two full years to become dominant (and he was mediocre last year after missing 5 games). Same for O-gun (also has his share of missed games), Abraham was good soon but is always hurt, Kiwi's 4 sacks aren't anything to crow about, Taylor is awesome but it took him 3 years to become consistently dominant. What I see is a) it take time to get good - not for all of them but for most -- Osi and Taylor are pretty good comparisons and b) some of these guys get hurt more than seems normal.
I'm sure Ware could eventually be good as a DE. But he's on the verge of being a GREAT OLB - OLB is clearly the position that suits him best.