SANTA CLARA, Calif. (AP) – Richard Sherman has a strong message for anyone still doubting the unbeaten San Francisco 49ers. “Don’t flip-flop,” Sherman said after the 49ers thumped the Cleveland Browns 31-3 on Monday night. “If you said we weren’t going to make it, you said we were some way early on, stick with that position. Hold it. Don’t try to give us credit now. At least stick by your word because I want you to sound like an idiot at the end. We know what we have in the building.” What the 49ers have is their best start since Joe Montana was throwing touchdowns to Jerry Rice. But it wasn’t the passing game that carried San Francisco past Cleveland. A steady, pounding running game and a dominant defensive effort did the trick this time. Matt Breida ran 83 yards for a touchdown on San Francisco’s first play from scrimmage, Baker Mayfield was harassed into his worst game as a pro, and the 49ers stayed unbeaten for their best start in nearly 30 years. Even then, there were some questioning San Francisco’s legitimacy. “I feel like they’re going to say that all year about us,” said Breida, who had 114 yards on 11 carries. “I don’t think anyone expected us to be 4-0 this year, to be honest. Probably expected us to be 0-4. They can say whatever they want. All that matters is who’s in this locker room.” Tevin Coleman added a 19-yard score as part of a dominant ground game on a day when quarterback Jimmy Garoppolo passed for 181 yards and kicker Robbie Gould missed a pair of field goal attempts and had a third try blocked. San Francisco (4-0) joined the 5-0 New England Patriots as the only remaining undefeated teams in the NFL. It’s the first time the 49ers have won their first four games since 1990. “It’s a good start is really all it is,” Garoppolo said. “We have a good mindset in that locker room.” The Browns (2-3) are headed the opposite direction after losing two of three, with fresh concerns about their young quarterback.