I think because of his experience, the coaches don't want to allow him to play yet.
They did not give Gink a chance to prove he was a better option rushing the QB, but once allowed, proved them wrong.
They did not think Achane deserved to be out there this early, but once they were forced to give him a shot, he proved he should have been out there earlier.
I like Fangio, and have no doubt in the end, he will get it done to bring a defense we can count on, but if they're holding back Smith because he needs to pay his dues 1st on only special teams, then he's doing a huge injustice to the defense if he does not know if Smith can do a better job in coverage then what we have.
There was a post a few days ago with someone saying there were plays on D where 4-5 players were standing around (sometimes together). Apparently weren't certain of their assignments. And none of them were rookies. Maybe it will take CS some time to get the assignments down. we know he looked like a natural CB in the PS