The defender was impressive in Bulgaria, dominated by the racist chanting of home fans.
Smith said, "Talking about his football first, extremely proud to see one of my players make his debut for England, assured performance, the biggest accolade I could give him was that it looked like he was playing for Aston Villa.
"He was organising people around him, was calm on the ball, the sort of performance we see regularly.
"Didn't get tested defensively but played his part in a good result for England."
He continued, "He's come back here and trained, got on with things as normal and not really said too much about it. I can only sing his praises.
"When we go and look at players and speak to them we know what they're going to bring football-wise, but it's that personality, character that you're looking to find out about.
"Me and JT went to meet him and he impressed us. Having met him, brought him here on loan and signed him – we've seen him every day and it doesn't surprise me how he handled the whole situation.
"He's articulate, intelligent and a very good human being as well."