There are good arguments for keeping another LB just like there are good arguments for keeping another guy on the D line. You could make a case for another O lineman, defensive back, or at almost any position on the team. If we could also predict where that extra depth would be needed then NFL teams would be lined up deep to hire us.
No way of knowing where you need that extra depth. I wish I knew. The beer would be on me Sunday if I had (and could do) that job.
Fitz makes bad decisions. That's not going to change.