Darren Ferguson bemoaned a lack of tempo from his Rovers side as their run of seven straight wins against neighbours Scunthorpe came to a grinding halt.
Paddy Madden netted the only goal of the game after 20 minutes as Rovers turned in a poor Boxing Day performance.
"We did the opposite of what I wanted," Ferguson said. "Even at start of the game there was a real lack of tempo and urgency to us.
"I think Scunthorpe probably turned up thinking it was a tough game and we wanted to make it that way.
"But it was really laboured. They've got an experienced team, especially in the middle of the park.
"And I think after 15 minutes they will have had a lot of confidence and thought they had a right chance.
"We went 1-0 down and in the second half we were slightly better, we huffed and puffed a bit more.
"But you can't have a first 45 minutes like that. It cost us the game."
READ MORE: Match report: Doncaster Rovers 0 Scunthorpe United 1 http://www.thestar.co.uk/sport/football/doncaster/match-report-doncaster-rovers-0-scunthorpe-united-1-1-7643928
Ferguson had spoken prior to the game about teams beginning to 'figure Rovers out' when it comes to system and style of play.
And while he praised Scunthorpe's approach, he felt the manner of Rovers' own performance led to the defeat.
He said: "I don't know how Scunthorpe prepared for the game but the longer we play the system, the better we've got to get at it.
"They've done what a couple of teams have done against us which is play three right up against the centre halves which means it's difficult for our wing backs to be released against their full backs.
"We worked a lot on that but the biggest thing for me is that if you don't keep the ball well enough, it becomes a very difficult game for us in any system.
"Tactics play a large part in a game of football but today it wasn't the reason we didn't get the result.
"They won every tackle, every second ball and that's surprising.
"We were way below what I expect from my team.
"It was a surprising performance and a disappointing one.
"We have to have the mentality that although we've been on an all right run, there is no reason for it to stop. We've just got to keep going, and keep hold of that mometum."
Ferguson confirmed Nathan Tyson is a doubt for Monday's trip to Oldham Athletic after being withdrawn 76 minutes into the clash with Scunthorpe.