That was the verdict of boss Grant McCann who was disappointed with aspects of play at both ends of the pitch in the 4-0 defeat.
"We've had a tremendous start to the season but you saw today with other results just how tough this league is," McCann said.
"If you want to step off it, and take your finger off the pulse, then you can get hurt. That is what we did.
"We made four mistakes that cost us the game really."
All four goals were preventable with Marko Marosi conceding a needless penalty just four minutes in which allowed Ched Evans to put Fleetwood ahead.
The next two goals came from headers from corners with Joe Wright caught in possession for the fourth, which effectively ended the game on 49 minutes.
Rovers had played some good football with the score at 1-0 and created plenty of chances, with John Marquis in particular guilty of missing a glorious opportunity.
McCann said: "I know this sounds really strange but we played well in the first half in terms of the chances we created.
"I just feel it was a tale of both boxes, conceding off two set plays, a couple of mistakes and then at the other end we didn't take our chances.
"We got what we deserved from that. If you don't take your chances and defend like that then you're going to punished in this league.
"It doesn't matter who you are up against and that was the case.
"I said to the group afterwards that we're all human. We all make mistakes.
"I make mistakes, the players make mistakes, my staff make mistakes.
"Unfortunately today we had four mistakes that cost us the game."