I certainly wouldn't say he can't....but I don't think you'd take a guy who played his career with his hand on the ground at #11 if you were going to designate him as an OLB who has to drop into pass coverage...I think the Spears selection is the best indication that Ware will play DE when we're in a passing situation if using the 4-3 and OLB rushing the QB from the 3-4...if he can also play 4-3 OLB, that will just be a bonus.
Spears is not a top DE if you're looking for a pass rusher...that's not his game....he's definitely here for DE in the 3-4 along with Ellis.
As to another question, I think Glover can still play some nose when it's a passing situation to rest Ferguson, and he'll try some 3-4 DE in certain situations...I don't look for him to play as many downs as he did last year.
The guy in Dallas reporting the selection, told us it was Spears about 1:30 before it was official, so he clearly was informed of this by the war room....he also reported that this was exactly how Dallas wanted it to fall, that they'd actually inquired 2-3 times about moving up for Spears with no luck....he said Dallas is definitely now moving to the 3-4 since they got the players they needed.
As the 42 pick came up, I wanted a WR, but I also couldn't help thinking we still are short on LB's for the 3-4 and considered we might take Dan Cody for another stand up guy, but then it was Burnett.