Video of 49ers and Browns players meeting at midfield for the coin toss shows Sherman walking down the line of Cleveland players, exchanging words and handshakes. When he gets to Mayfield, he appears to have some kind of physical interaction with the quarterback, though the video makes it unclear whether it's a full handshake. Sherman also says a few words to Mayfield.
"What's amazing, and annoying, was him not shaking hands at the beginning," Sherman said Monday night, according to NFL.com. "That's some college s---. It's ridiculous. We're all trying to get psyched up, but shaking hands with your opponent -- that's NFL etiquette. And when you pull bush league stuff, that's disrespectful to the game. And believe me, that's gonna get us fired up."
After video of the pre-coin flip interaction went viral, Sherman told The MMQB on Tuesday afternoon that the 49ers were angered that Mayfield darted away immediately after the coin toss.
"That's it. They are making way too big of a story of a blowout," Sherman is quoted as saying. "He pissed us off. We put a foot in his ass. End of story."
On Monday night, Sherman was adamant that Mayfield had crossed a line by not shaking hands.
"Respect the game," Sherman said, according to NFL.com. "You can have rivals, but pay your respect in that moment -- especially when you're young.
"He hasn't earned anything in this league. How many games has he won? He's acting like he was the MVP last year. If [Patrick] Mahomes did that, it would be one thing. But he would never do that, because he has too much respect for the game.
"And when you see a guy who doesn't? You humble him every chance you get. Because eventually, he will have respect for the league -- or he'll be out of it."
When fans on social media questioned Sherman's assertion that Mayfield didn't shake his hand, the Pro Bowler doubled down in a number of responses on Twitter.
He later deleted many of those tweets.
Sherman also addressed the pregame interaction Wednesday on Westwood One's "The Pat McAfee Show." He told the former Colts punter that he may have remembered the interaction differently than what happened but said he still felt Mayfield was being disrespectful.
"I put my hand out, you know, just out of courtesy, and he gives me a petty little, you know, slap on the hand," Sherman told McAfee. "I took it as disrespect."
Sherman also acknowledged how he described the moment to NFL.com but stood by what he took from it.
The Browns had no comment on the situation Tuesday.
The brash Mayfield was the focus of Niners' ire all night.
Defensive end Nick Bosa harassed the QB into an intentional grounding call and then pretended to plant a flag -- mocking Mayfield's planting of an Oklahoma flag at Ohio Stadium in a 2017 game against Bosa's Buckeyes.
"I think everybody knows what that was for," Bosa said. "I just wanted to get payback. He had it coming."
Sherman intercepted Mayfield on the Browns' second possession on the way to the 49ers'31-3 blowout.
This isn't the first time Mayfield has been involved in a handshake controversy. Before a 2017 Oklahoma-Kansas game, Jayhawks captains refused to shake Mayfield's hand during the coin toss.
During the third quarter of Oklahoma's blowout win in Lawrence, Mayfield grabbed his crotch and appeared to yell "F--- you!" at the Kansas sideline. As punishment, he did not start or serve as captain for the Sooners' next game on Oklahoma's senior day. Kansas also stripped its three players involved of their captaincy for its final game of the season.
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