Two goals from on-loan striker Jack Midson earned the struggling Shrimpers their third away win of the campaign and ended the Robins` six-game unbeaten run.
It came after the first meeting was abandoned due to floodlight failure, with Town leading 1-0, and the rescheduled clash postponed following the big freeze. Yates said: "That's the poorest performance we`ve had this season and I'm a bit embarrassed by it to be honest.
"We got bullied in all departments and we just have to draw a line under it. I found a few things out about one or two, but we have to turn all this into a positive.
"For the first 20 minutes we couldn't clear the ball, we couldn't pass the ball, we couldn't do anything. We huffed and puffed in the second half, but it was too late.
"I don't want to see a performance like that again, it was disgusting. Maybe that's the kick up the backside we needed. Maybe one or two of them are getting carried away a little bit with talk of the play-offs."
Source: PA
Source: PA