I like both Mercilus & Brooks, lets see how Crennel uses them first but yes - add another edge rusher.
If they go with Clowney , he likely plays OLB .... Making it possible to move one of Mercilus / Reed inside , killing two birds with one stone , that is pending one of them has the ability to play inside.
Solving two positions with one draft pick would be making a big impact .... Tho I doubt that impact would be as great as having simply competent QB play.