Hopper has a 7.38 RAS acore at LB, meaning he ranks just under the 74th percentile athletically among linebackers historically. That's an above average overall athlete at the position, and well beyond the vast majority of people in general.

He's a little small size-wise, but that's how LBs are these days.
He has good enough speed and get get to the sideline just fine. His biggest issue is tackling.
Hopper fits what Hafley is going to want his LBs to do -- all of the defensive picks this year were aggressive, downhill attaching types who have good character and love football. I think Hafley is going to ask them to shoot a gap and not do a lot of thinking or reacting.

I'm NOT on the Hopper bandwagon, I think there were other LBs (or players at other positions) they could have gone for that i would have liked, but Gute isn't trying to please me specifically with his picks.
Either way he's a Packer and he's got a shot, so I'm rooting for him. This could be the return of the 3rd round curse.