The Black Cats had lined up a transfer for Richards at the start of the season, but Poyet felt he would be an unnecessary addition and stopped the move going through.
In the end Richards went off to Fiorentina on loan and Poyet's decision to stop Richards' transfer going through has reportedly frustrated the Sunderland board.
The Uruguayan manager is tipped to be getting the sack in the coming days and this decision has apparently played a part in his dismissal.
Would Richards have made a difference at Sunderland?
Almost certainly. The England international would have provided the team with strength and pace and could have covered at right-back or centre-back.
Sunderland have struggled for defenders all season and Richards' addition would surely have given them more options then they have now.
The likes of Billy Jones and Santiago Vergini were both expected to compete for the right-back berth at the start of the season, but neither have looked particularly impressive and Sunderland were forced to bring in Anthony Reveillere on a free transfer to cover for their problem position.
Although the experienced Frenchman has done a decent job, he doesn't have the quality Richards has and it is rather baffling why Poyet decided against signing the Manchester City man, when he had the opportunity.