Rivera knows defense but is he really any better than a generally average/above average HC?
Sure, they'll be better with him considering the clown show they are right now but are they really going to do any better than their standard 8-8/7-9/fluke 9-7 or 10-6 playoff appearance/6-10 dance that they've been doing for 15 years?
He'll have them hovering around 8-8 most years, and I'm sure there will be a playoff appearance mixed in here and there when the rest of the division is down, but I don't see him turning them into a real contender, especially not with shit bird Haskins at QB.