I agree with Harris as being one of the top pure pass rushers but that's all he can do. He quits on run plays and has no pursuit. He seems almost selfish as a player cause if he's not getting the sack then he doesn't care. (May be totally not true) that's just what I see as a more than casual fan.
Tak on the other hand is no where near the skill that Harris has but he goes all out on every play. He gets his sacks with just pure effort and fight. I like that in a football player. Without knowing too much about him but players like that can be coached up but he is for sure a project.
As for Thomas, I just watched most of his bowl game and dude is smart and strong. He diagnosed a few screens so quickly I was very impressed. He does rarely rush for the edge and he for sure would need to work on that. But he extends very well and fights through double teams. I like him a lot but maybe not enough to say we "need" him.