Wright was on Monday confirmed as the Perth outfit's new manager after Lomas quit to take over at Championship side Millwall.
Saints chairman Steve Brown has also announced that current McDiarmid defender Callum Davidson will act as the new boss' number two.
And Millar - Saints' second-longest serving player - says Brown has made the correct call in promoting Wright to the top job.
He told Press Association Sport: "Tommy is the right man for the job. His appointment will bring continuity to what we did last season.
"He was a big part of the success we has last year being Steve's assistant and bringing in Callum as his number two is a really good move as well. He knows all the boys and will bring a great deal of experience as well.
"He's played at a really high level and it's a really good appointment. All the boys in the dressing room are really happy with it I'm sure.
"We will miss the gaffer with him going south. He did a fantastic job. But it was a move he wanted with his family being down there and it was the right time for him."
Wright is currently on a family holiday but will be unveiled at a press conference on Tuesday, June 18.