Since several of my LBs got moved to DE (e.g. Micah Parsons) I am thin at LB. Does that make you reconsider?
Ah, the true position MFL change. I had the exact same scenario with Parsons happen to me, and I thought long and hard about Campbell, but went in a different direction. Young LBs are no sure thing these days, and it takes a while to get used to being in modern coverages for LBs. Now, Campbell could come in and be an uberstud and prove me wrong, but I'd suspect it might take a year.
So that's a consideration. You seem to think you're a contender, therefore If you have older RBs and a solid WR corps, then you might draft an RB with the 1.8. Mattison, in my opinion, is indeed JAG. It's just whether or not you can get anything out of his replacement at 1.8 this year.
That's probably not too much help, but it's commiseration and a thought process.