This is considering Ware being used conservatively. Lined up in the same spot over and over, without much help scheme-wise. On the other hand, we'd see other teams' pass rushers somehow end up on a RB, off-balance blitz or coming from various spots.
Furthermore, Ware was a fantastic run-stopper, great at preventing the runner from getting around the edge. A more selfish Ware could've gotten more sacks if he wanted, but at the expense of more big running plays.
I think Ware could easily have 15 more sacks.