Bullen is first-team coach at Sheffield Wednesday and helped convince manager Stuart Gray to move for the striker when it became clear he could be tempted from St Johnstone at the start of the season.
The former Dunfermline and Falkirk player has since watched May win over supporters with his wholehearted approach and eye for goal, with the 21-year-old grabbing three goals in 12 appearances for the Championship club so far.
Bullen believes the team spirit being fostered by Scotland manager Gordon Strachan could help May to make an immediate impact at international level as well.
He said: “He’s settled in really, really well at Sheffield Wednesday. I had been keeping tabs on Stevie for a while. It’s not a ‘moneyball’ scenario where you look at every stat but somebody that can knock the ball into the back of the net with that regularity was always going to be a decent signing.
“He’s proved that at the moment with his work-rate; he’s unselfish, he’s a team player. He’s quite a quiet lad but, slowly but surely, he’s coming out of his shell and I think getting a couple of goals in the first few games has set him up well.
“There seems to be a right good togetherness about the group and the players involved with Scotland, and that will make it slightly easier for Stevie there as well. For his first international call-up, he’ll be going into a group with no factions, no splinter groups, no them-and-us mentality. It’s ‘all-for-one’ and hopefully that gives Stevie an opportunity.”
Meanwhile, Scotland midfielder Shaun Maloney is now fully fit, according to his manager at Wigan, Uwe Rosler. The 31-year-old completed his first full 90 minutes of the season in what was only his second Championship start for Wigan in Saturday’s 2-2 draw at Wolves. Rosler reckons the player is now in peak condition.
He said: “Shaun Maloney has been introduced quite a bit lately. I started him against Ipswich and I wanted him on the pitch. He did his job exceptionally and he is now 100 per cent fit.”