The £250,000 bargain buy from Rotherham during the summer had been exceptional after stepping in for John Filan as the Australian recovered from a hernia problem.
But Filan returned for the Carling Cup second-round win over Bournemouth last week and then surprisingly retained his place in the side for the 1-0 league victory at Everton on Saturday.
Jewell said: "It was a tough decision to leave Mike out, one of the hardest I've ever had to make because he has been fantastic for us. I just felt it was the right time to bring John back in.
"Obviously, "Polly" wasn't best pleased and I understand that. What was difficult was he hadn't done anything wrong and I'd told him previously if he played well he would stay in the side. I went against that... I just had a gut feeling it was the right thing to do."
But Jewell has warned Filan that he cannot afford to let his standards slip, otherwise he will have no hesitation in recalling Pollitt.
"I've two great goalkeepers in competition for the shirt, and I think John will realise now he has to play very well to stay in the side."Reuse content