I think a lot of you are really confused here.
Both the weakside linebacker and middle linebacker have significant run stopping responsibilities. That being said so do the corners.
It isn't just on the defensive tackles. The ability to stop the run in the tampa 2 depends much more on the linebackers and the secondary compared to the defensive line in the 4-3 or 3-4.
Much of the success of our team depends on how Carter, Lee, Claiborne, and Carr play against the run. It's also vital that the defensive line create a pass rush, mostly without blitzing. That being said pressure is much more important than sacks. We don't necessarily need to take the QB down, but we can't let them get all day like they have been recently in the 3-4.
The difference between the 4-3 and 3-4 pass rush is significant though. In the 3-4 you would have Spencer and/or Ware pass rushing predominantly. And the role of the 3-4 linemen was mainly to stop the run. So that is often why you wouldn't see significant pass rush for our players. You're not generally going to get much pass rush from players who weigh 315-320 lbs. In the 4-3 especially this one, your average weight drops to 273.... Pass rush certainly becomes easier at that point.
I remember how people were clamoring for us to have Spencer, Butler, and Ware on the field at the same time in the nickel, we're going to do that with Rayford essentially, and now people aren't pleased...
The defensive line shouldn't be nearly the problem people think it will. And there really isn't any great solution to it at this point, except waiting for it to become healthy. I have no doubts that a line with Ware, Hatcher, Spencer, and Ratliff is going to be able to wreak havoc with their focus being pass rush. Very different from what you would get with that coming from a 3-4 look.