The Tractor Boys were four points adrift at the bottom of the npower Championship table when McCarthy, and assistant Terry Connor, took the reins at Portman Road, but five wins from nine games has lifted spirits.
Chambers, who signed a three-year contract with the Blues in the summer, thinks McCarthy's selection process has had a major effect.
He told the East Anglian Daily Times: "The gaffer has made no secret that if you are not performing to your best and not buying into what he wants, you will be out.
"They have come in with their own ideas and the lads have bought into them quickly.
"Maybe, people who were possibly comfortable in the team under the previous manager have found that it is a new start for everyone."