Lomas begins his reign on Monday night against Aberdeen in the Scottish Premier League after being appointed as the successor to Derek McInnes.
McInnes left St Johnstone firmly ensconced in the top half of the SPL but the team did not score in the two games since he left for Bristol City, losing at home to St Mirren last weekend.
And McArdle expects the arrival of former Northern Ireland and West Ham midfielder Lomas to have a positive impact.
"I think the fact they have a new manager will give them a lift," McArdle said.
"You see throughout football when a new manager comes in automatically it brings a massive lift to the club.
"Albeit their the new manager is coming in after the success Derek McInnes has had, so there will be a bit of pressure to progress.
"Hopefully we can go down there on Monday and spoil the party."
The Northern Ireland international added: "I don't personally know Steve Lomas or Tommy Wright but some of my friends have played under Tommy and they have all spoken very well of him.
"I'm sure both of them working together will do very well.
"Steve has a lot of contacts in the game so I am sure he will put them to good use."
Aberdeen are looking to recapture the winning form they had found with wins over Dunfermline and Dundee United before suffering 2-1 defeats to both halves of the Old Firm.
"I thought we were unlucky not to to take anything at all and on the back of playing them it has pushed us down the league a bit," the full-back said.
"It is therefore important we take something from the game on Monday and go on a run.
"Now we are creating really good chances and with the quality we have up front we are going to take more chances than not.
"We have looked far more solid from a defensive point of view as well.
"There is no fear factor going down there. We know it's going to be tough but it's not a place where you would sit in and try and nick a goal.
"There is no reason we can't go down there and have a go and get up the league."