Scotland midfielder Commons returned to the starting line-up for the champions' shock 2-0 home defeat to Kilmarnock at Celtic Park on Saturday.
He is certain though that the Hoops, runners-up to Killie in last season's Scottish League Cup, will bounce back from back-to-back defeats which included a 94th-minute Champions League group match defeat in Barcelona, when Saints visit Celtic Park.
"Our attitude wasn't right from the start and it's hard to put into words why," Commons said. "I think playing for a club like Celtic you have need to get some middle ground of what's required in a game, whether it's Camp Nou or in the SPL.
"You can't expect to play so well in one game and then put in that sort of performance, in two games we've gone from one extreme to the other.
"We've gone from being really good defensively, everyone working hard off the ball, and everyone wanting to help each other to looking like strangers out there - looking like lost boys.
"I know a few came into the side, myself, James Forrest, Beram Kayal, Miku and Adam Matthews, but we've been playing together for years now so it should just click together. Once one goes in, one goes out, and it should slide in nicely but we looked like a lost team.
"The manager was bitterly disappointed and he obviously wasn't happy with the performance or our work rate. There was no desire to win the match and we as players demand a performance that's acceptable, but obviously everyone was unacceptable against Kilmarnock."