Simpson blamed the results on dressing room unrest, and 35-year-old Alexander felt he should have been stronger with his team-mates.
But Simpson, who quit as Carlisle boss to take over at Deepdale last summer, insists the entire team should shoulder the responsibility.
"I spoke with Grezza about that and I said I thought he was a bit daft saying what he did," Simpson told the Lancashire Evening Post.
"I don't hold him responsible at all. It looked from what he said that he was shouldering all the blame and I don't believe that is necessary. I think everyone as a group has to take the blame.
"Graham Alexander does not need to take the stick. He doesn't need to take all of that responsibility. He has been a fantastic captain for us this season.
"And over the season he has been consistent the majority of the time. He is still a full international. I think everyone needs to look at themselves, especially me. And I will definitely be doing that over the summer."