I'm not a scout, but I don't see what everyone else see's in Foster. To me he looks like he's slowed down on the field because he's thinking too much. As a result, he seems to play smart, but reactionary football.
On the other hand, watch someone like Haason Reddick play. That guy attacks the offense and just plays faster.
Cliche to say this, but Foster has a higher floor, Reddick has a higher ceiling. But I'd take Reddick over Foster all day.