I'm not sure what your requirements are for "really well", but they're definitely different from mine.
In a season of great surprises, Tyrone Crawford and his undeserved contract are a huge disappointment. And very likely, a big factor in this team's reluctance or inability to bring in a better defensive lineman.
Crawford was paid to be this defense's Warren Sapp, and he has failed to live up to it. So much, in fact, that he's been replaced at 3-tech and is taking up space at defensive end due to a lack of options, while contributing to an underperforming pass rush. He plays a key role in the team's biggest weakness.