It was all a misunderstanding.
Richard Sherman has always been one of the more vocal players in the entire NFL and right beside him in that crusade is Cleveland Browns quarterback, Baker Mayfield. The two see to have very similar personalities that tend to clash at times. This was apparent during Monday Night Football when after the game, Sherman alleged that Mayfield wouldn't shake his hand during the pre-game coin toss. Based on visual evidence of the interaction, this was most certainly not the case as you can clearly see Mayfield extend his hand.
After being called out for making false allegations, Sherman realized it was time to apologize and hit up The Pat McAfee Show to clear the air on what happened. As Sherman said, he hopes to apologize to Baker and eventually make things right.
"It's definitely my bad," Sherman said. "You know, I never want anybody to have to deal with ... some stuff that they didn't do. And, so the questions that he's gonna get and the annoying, nonsense questions about some stuff that happened in a game that's already been done, sure he'll get an apology for that."
Sherman ended up getting the last laugh in that game as his 49ers won the match by a score of 31-3. Mayfield has struggled so far this season and it's clear that he has much bigger fish to fry than a handshake.