John Marquis, Mallik Wilks, Herbie Kane, Andy Butler and James Coppinger - along with suspended goalkeeper Marko Marosi - were all absent from the matchday squad as Rovers went out of the competition with a whimper.
But McCann, whose side visit early League One leaders Peterborough United on Saturday, stood by his decision to ring the changes.
“No regrets,” he said after the 2-1 second round defeat.
“Everything is lovely in hindsight isn’t it, really?
“I’ve got no regrets whatsoever.
“We went one nil up and we were on top of the game and then we concede from a corner.
“In the second half we didn’t get around second balls enough. I don’t want to use the word ‘bullied’ but I think the physicality of their team told. We couldn’t cope.
“But there’s going to be ups and downs this season and it was a League Cup game.
“We’re disappointed we’re out but the priority, like I’ve always said, is the league and making sure we keep ourselves up there.”
McCann handed opportunities to Ian Lawlor, Tom Anderson, Jermaine Anderson and Paul Taylor to stake their claims for a regular spot, while winger Matty Blair was handed his first chance to impress in the front three. Alex Kiwomya, Alfie Beestin and Issam Ben Khemis also featured as second half substitutes.
McCann said: “What it told me was that if anyone was waiting and thinking ahead to the Peterborough game then they could find themselves very easily out of the team.
“If one or two were coming in and thinking ‘I should be in the team’ they need to think again and keep themselves away from my door.
“Some of them showed themselves that they are just not ready at the minute.
“What it did do was give them an opportunity to get some minutes under their belt.
“It was an opportunity for the boys that came in to show they should be knocking on the door but it didn’t happen.”