With only one point from the last possible 21, Steve Parkin's men have changed from promotion contenders to candidates for the conference.
Stockport County found the chinks in their armour after Jermaine Easter had put County ahead on seven minutes with a speculative scissors kick. After that, Rochdale never looked forward and Stockport never looked back.
Rochdale were limited to one good chance nearly taken by Alan Goodall late on but his on-target shot was spectacularly saved by James Spencer in the County goal.
Rochdale produced very little by way of chances, although they enjoyed most of the possession without making much of it. The home defence was not without its weaknesses and Easter came very close to making it two and possibly even more.
Fifteen minutes from time County missed a penalty when Matthew Hamshaw put the ball over the top from the spot after he had been brought down by Rochdale's John Boardman. Justice was done because the penalty kick had a dubious look about it, Rochdale's players seeming to think that the referee had blown to book Hamshaw for diving.
Rochdale made very few chances because they dithered around outside the penalty area and appeared reluctant to have a shot on goal.
Perhaps it would have been different if they had not sold Grant Holt a few hours earlier to Nottingham Forest for well over £300,000. Rochdale missed Holt badly especially as, while they were floundering around; Holt was getting a goal for his new side against Oldham.