The two teams played out a one-sided FA Cup third round contest at Portman Road.
Despite going into the contest with hope, Rovers were unable to match the Premier League minnows.
“I think the big thing was in the first half,” Calderon said at his press conference.
“I don't think we started well enough. I think we showed them too much respect. I don't think we were good defensively. Especially when you want to try to defend high up the pitch, you have to do everything perfect and when we had the ball, we couldn't keep it at all.
“So I think it was coming in the first 15 minutes. You could see that the goal was coming and we couldn't stop that and listen, there is the difference. That's why they play where they play and that's why we play where we play.
“We knew that we had to do everything perfectly to have a chance to win it and I don't think we did in the first half, especially.
“It's true in the second half that I think we improved. I think we were improving during the game but, as I say, I think that’s the price when you play a different style of game. Last game we played Cambridge away, that was a completely different to this game and we have to adapt and we have to learn during the game and that's not the best thing.”