I'll disagree here, I think he's very very good. He's shown the intelligence to sniff out screens and run plays and he's a strong tackler. He's superior to Edmunds right now in every way.
Otherwise, I think McD will just have to change the scheme. No more basic four-man rushes, he's going to have to send guys like Taron Johnson or even Poyer in on DB blitzes to get to the QB quickly. That's all he can do right now barring a trade for someone like Dontare Poe.