But it is Johnson who has been involved in virtually every game since the start of the season in aiding McLeish to overcome an injury crisis at the heart of the back four.
And he has quickly won over the City fans with his bravery and never-say-die attitude in helping his side make a reasonable start to life back in the top flight ahead of Sunday's clash with Wolves at Molineux.
Johnson said: "When I first signed, I said it was a big step-up for me and that every game was going to be different - and I feel as if I've done okay so far.
"We've kept a few clean sheets and it has gone fairly well. Obviously, one mistake gets punished at this level and positioning, knowing where the forwards are, is a lot different to the Championship.
"It is important to concentrate on where you are on the pitch and be aware of not losing your marker.
"But football is my life and I've watched the Premier League since I can remember, since it started. It is nice to finally get a chance at this level.
"You think 'can I play there' and, touch wood, so far it's gone to plan and I've made the step up okay. It is the best league in the world. I am playing the best players in the world.
"Everyone was expecting big things, signing for £5million, and I don't think I've let anyone down so far so long may it continue."
Birmingham have shown their potential during a four-game unbeaten run which saw them overcome Sunderland and Fulham and share the spoils with Manchester City and Liverpool.
But Johnson is aware of the importance of picking up points during the next run of games against the likes of Wolves, Wigan, Blackburn and West Ham.
He said: "The confidence is high in the camp and the games we've got to win are the ones against the teams that will probably be around us in the table. We've got a good little run of games now with Wolves, Wigan, Blackburn and West Ham. We've got to pick up points."
McLeish has challenged his players to maintain their current form against Mick McCarthy's side.
He said: "It's a nice feeling to be up to 15 points but we've just got to keep building on it. The evidence is there for the players with the games they've played so far.
"We've played 13 games and 12 have been to a very decent standard, with the one at Burnley being the exception.
"But we've got to keep our feet on the ground. There are hard games coming up and you just can't guarantee anything in this Premier League."
Wolves 11/8, Birmingham 2/1, Draw 9/4