I don't know why you would recruit a player who has no physical skills and low mental capacity?
I would see recruiting a stud CB for instance, who is great cover guy, but not smart to be kind...and just give him a guy to cover each play.
A smart player....who is limited physically can work. But position matters. A run stuffer for instance.
your players need some smarts today. offenses are complicated(so offense needs be smart) and defense needs guys who can think and move at same time.......defending RPO is not easy.
Also you see so much hurry up stuff they need be able to take call from sideline, digest it and execute their assignment.Defenses don't get to huddle anymore.
Fictitious example......lets assume Ed Oliver is not smart(we know he is) but he's still Ed physically. You just give him a gap to blow up each down.........you know that gap is accounted for and have smarter guys play around it.
Centers need be smart and can be limited physically but strong., LBs due to run and pass responsibilities every down need be smart and have physical ability, need to run. Safeties make a lot of calls and need be smart. QBs obviously