Phillips came off the bench to score a late goal against Bolton last weekend, although it ultimately proved in vain in a 2-1 defeat.
McLeish is almost certain to be without Christian Benitez against Burnley on Saturday as he has flown back to Ecuador after his father was involved in a car crash.
But he is still likely to persevere with Phillips on a bit-part basis as Birmingham look to halt Burnley's run of three successive home wins.
He said: "Do I still see Phillips mainly as a substitute? I do.
"Let's make no bones about it. Kevin is 36 now and I want to see him strutting his stuff on the training ground as well and helping other players, and he has a part to play in that sense.
"I also want to see Kevin playing with a smile on his face as he did last week. He came on and was extremely bright and this week in training he was bright.
"I still see that as his most significant role, coming on and doing what he did last week.
"Kevin might argue and feel he can start games. I've got to be the judge of him and we can get the best out of him doing what he did last week."
McLeish added: "I'm not saying he'll never start games because I also had this conversation at the start of the season and then played him at Stoke for 90 minutes and the Sunderland game for 90 minutes.
"In the Sunderland game he didn't look himself. He didn't have that smile we associate with Kevin when he is enjoying his football and linking in with the strikers and the midfield.
"But last weekend, after I had a chat with him after the Sunderland game, he was buzzing."
McLeish is full of admiration for Burnley boss Owen Coyle and signed him as a player when manager of Motherwell.
He said: "I signed Owen for Motherwell and he was very instrumental in scoring goals that took us up to the Premier League.
"I saw him in one of his last games for Bolton in a play-off final and I knew he could do a job for me in Scotland and I'm not surprised he has done well in coaching and management.
"He is a modern breed manager who is always very positive, the cup is always half full, and I'd like to think I've taught him well.
"He worked under me for a couple of years and I'm sure some things have rubbed off but he has got his own personality as well.
"He was always very vociferous in our dressing room but always in an encouraging way and he could already understand then that the manager's lot is not an easy one.
"He was always a guy who would back me in any dressing room points that I had to get across. He was always right by your side."
McLeish insists Blues have nothing to fear against the Clarets after encouraging performances away to Manchester United and Tottenham.
He said: "Burnley will point to their home form as being different to their away form but at the same time we have got to go there with the belief we can win that game.
"I don't see why not considering our form and the confidence we have shown in all the other games.
"The away games are tougher but we have proved in our away games with Manchester United and Spurs that we can live with them so why should we fear anything?
"The evidence is there. It is not like we are looking into the land of the unknown."