Rovers were poor from start to finish and proved easy prey for a side that sat just one place above them in the table prior to kick-off.
Lacking any cohesion or threat in possession, they also made countless errors off the ball and were picked apart with Elliot Lee, Ben Purrington and Jayden Stockley all netting, alongside a penalty from Conor Washington after Tom Anderson fouled Alex Gilbey.
“That was hard to watch,” Wellens said.
“You come to a club like this that have had a massive transition in the last seven days and you can feel it in the ground.
“We did not compete - first balls, second balls.
“Stockley will have a headache tonight because he’s won every single header in both boxes and from every ball up to him. He’s had an easy ride.
“When you come to a club that are on the turnaround and they’ve got really good players and first of all you don’t compete, then you’re not in for a good day.
“For the first 15 minutes there was nothing in the game and then we make a poor decision to give away a stupid free kick, which we did consistently throughout the game.
“And everything we spoke about in possession and out of possession we didn’t do. They’re a really good counterattacking team and you can’t afford to give the ball over in the middle of the pitch.
“We consistently did that.
“We worked on if their wingbacks are aggressive and high then get balls over the top, into the channels and get Joe Dodoo up against Jason Pearce. We didn’t do it.”
The Rovers boss feels recent good performances may have lulled his players into a false sense of security in their approaches.
And he labelled the defeat at The Valley a stark reminder of how difficult life can be if the battling side of the game is not taken care of.
Wellens said: “Maybe because we’ve played well in the last few games with the ball, we think we can go and dominate the ball.
“But if you don’t earn the right then that’s never going to be the case.
“First and foremost that you expect from a Doncaster Rovers player is to fight and earn the respect of the supporters, and show the desire you want to work for the first. I don’t think we did that.
“And our decision making contributed to that. It wasn’t through lack of effort, it was our decisions.
“And it could have been more.
“They’re a good side but we allowed them to be better.”