Earnest Brown already proved he's a good MIKE LB. The question is not whether he's good but who will play around him? With the Rams being very deep at OLB, they could play a lot of one ILB (Jones). Johnson is listed as a OLB but he plays better inside which would make him an ILB.
Bobby Brown was drafted because Morris wants to play a Fangio style read/react DL with a 0T NT. Gaines was allowed to walk because of Morris. Gaines is a damn good 1T NT but Morris insists upon playing soft on early downs so he wants Brown to play a 2 gap 0T NT. In that scenario, Bobby Brown is simply a blocker eater counting on the LBs behind him to make the plays. Morris could play Mathis as a WIL behind Hoecht which would give Jones support on run downs. Morris could also play Hampton as a SAM OLB in the same way Philips used Ekubam. Why? Because with a WIL and SAM playing with OLB they have better physical size to play contain for the many mobile QBs the Rams will face. It would also take away those short dumpoff passes.
It will be interesting to see what defensive alignment Morris trots out there in TC. I've pointed this out in other posts so I didn't feel the need to belabor the point.