The Scot is currently at the Euros as part of Steve Clarke's Scotland backroom team.
“I think I was the third (set-piece coach in the Premier League) when I joined Aston Villa,” he told the Scotsman. “Brentford and Arsenal already had a set-piece coach. I think there are now 13 in the league. Chelsea bought the one from Brentford for £750,000!
"Manchester United’s set piece coach went straight from being the set-piece coach to the manager of Minnesota in MLS, so there is credibility in the role. (Ange) Postecoglou is asked whether he wants one every time they (Spurs) lose a set piece. That speaks volumes.
"Set pieces will be certainly secondary to team performance but they are also linked. If we can get the performance from the team we will have more corner kicks and free kicks and concede less. If we don't perform to our capacity, you’ll end up defending 15 corners in a match and having one, so it becomes so important to have the ball."
He added: "When you go to the edge of the pitch, at Villa I always go to the edge of the pitch, at Hampden sometimes not, as it is so far. But the general idea is that in that moment you are responsible.
"If you go to the edge of the pitch when you are defending a set piece, there is no upside – because everyone thinks you should not concede a goal, and you might. See if you go to the edge of the pitch in an attacking set piece, supporters think you should score – and you might not.
"There is an empathy between people in my job because you could lose the game off one and you are totally responsible. But that’s also the beauty of it. You are very involved in the outcome of the match."