It was a second 1-0 defeat of the week for Posh who are now eight points outside the play-off places with 10 games to go.
McCann blamed an error by goalkeeper Luke McGee for a scrappy City goal midway through the first half, but reserved most criticism for the team’s flair players.
McCann selected an attacking formation, but they barely created a scoring opportunity against a team unbeaten at home this season.
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“I had all my creative players on the pitch,” McCann stated. “Marcus Maddison, Paul Taylor, Tom Nichols etc were all on the pitch, but they played like individuals.
“We work so hard on one-twos and link up play, but none of that was transferred onto the pitch today.
“We never looked like scoring a goal by carving them open. We had a couple of opportunities - most notably through Tom Nichols in the second half - but they had several chances in the second half.
“We keep playing teams who create little, but manage to score. We haven’t mastered that art. I keep saying when you are not playing well, especially away from home, then make sure you don’t lose.
“But we made a bad mistake and we were punished. For a goalkeeper of his ability Luke McGee should have done better with the shot, although there was also a missed tackle from someone and a missed opportunity to clear the ball by Andrew Hughes.
“It’s a dressing room that is hurting now. I am hurting. My weekend has been ruined, but we will pick ourselves up and have a good week’s training before the Oxford game next Saturday (March 11).
“We haven’t been good enough since January, but we will try and string some wins together and see where we end up.
“As a minimum we have to win our five home games and hopefully nick a couple of away wins.
“Others wrote us off a long time ago. They think we don’t have a cat in hell’s chance of going up, but we can’t afford to think like that.
“The play-off places are not set in stone. A team in the top six will have a dip in form and we have to make sure we are in a position to capitalise.”