Why don't you think Simmons can play ILB opposite Hicks?
Only if you want to make a big gamble and do exactly what every Cards fan as slated Keim for doing with Reddick and Buc.
Simmons is a SS / Will/Sam backer / slot DB. I think he fits a 4-3 scheme best where he can rush from outside backer and cover TEs.
He may turn out to be a good inside linebacker with some work but I don't think you can draft him as that.