He wasn't Sauce's guy on that play. They are in zone, Sauce is really responsible for the outside but reads where Josh is going and tries to dive across and make a play and just misses. That wasn't Shakir running a route vs Sauce and getting the better of him. Also, that was a route ran from the slot where Shakir gets a totally free release. The #26 looks as though he might go and engage but lets Shakir go and plays his responsibility to the flat.
The reasons he can't play outside regularly are the same as they've ever been for me. Short arms, struggles getting off press and will get bodied out by bugger corners at the catch point.
Shakir is a good player. He is a slot receiver.