Dale take the points on the final day.
In what has been a tough season for the U's, they fell behind midway in the first half, before Joe Edwards' fine strike at the start of the second drew things level.
But Calvin Andrew showed some class late on to bend one in the top corner and give the visitors the points.
The match saw two U's players make their debut, as James Bransgrove took up position between the sticks and Cameron James came off the bench in the second half for 25 minutes at right back.
Young shot stopper Bransgrove was assured in his keeping, but could do little about it when Dale took the lead.
Edwards got caught on the ball in midfield by Mendez-Laing and he broke clear alongside former U's man Ian Henderson.
The duo swapped passes, before Mendez-Laing slotted home into the bottom corner.
With the heat bearing down on the Weston Homes Community Stadium, the match was a little stop start and whilst Dale had the better of possession in the first half, the U's probably had more chances.
They made those opportunities count at the start of the second half when Gilbey showed good persistence to lay the ball back to Porter, who in turn set up Edwards to fire home into the top corner.
Porter came on after U's had lost Macauley Bonne to injury, and they then lost goalscorer Edwards just after the hour mark.
Cameron James came on for his first U's match and slotted in at right back, and did well in his stint on the pitch.
Bransgrove had pulled off one superb stop low to his left from Andrew, but could do little about the big forward bending one into the top corner beyond his despairing dive.
The match slowed down somewhat after that, but the U's kept pushing right to the final whistle, with Lee's low cross skimming across goal without the final touch.
The season is over and the U's will have to dust themselves down over the summer before they prepare themselves for a promotion push in League Two.
Thanks to all of the fans who came to back the boys this season - here's hoping for a positive campaign in 2016/17!