SAN FRANCISCO — Maybe it was the removal of the small caterpillar on his upper lip that he referred to as a “mustache.”

Maybe it was the reemergence of “Walter,” his nasty, pitch-firing alter-ego celebrating a holiday afternoon.

Most likely it was the combination of consistent command and conviction with his plus fastball and stellar secondary pitches.

In front of a packed crowd at Oracle Park on Tuesday, Logan Gilbert delivered the best outing of his career.

On his 105th and final pitch of the game, Gilbert ripped a 97-mph fastball at the hands of Michael Yastrzemski, who helplessly flailed at the pitch for strike three.

After his legs and arms unfurled from his vicious delivery, Gilbert pumped his fist and screamed in celebration. He’d thrown his first career shutout in a 6-0 win over the Giants.

Gilbert allowed five hits and struck out seven and didn’t issue a walk.

Born on the Fourth of July, Michael Harrison Ford celebrated his 31st birthday by banging out four hits in five plate appearances, finishing a triple short of the cycle, which isn’t surprising, while also scoring two runs to ignite another productive offensive attack.

Seattle has won a season-high four games in a row and made it back to .500 at 42-42.

The Mariners jumped on spot starter Keaton Winn, who was announced as the starter less than 24 hours earlier. J.P. Crawford led off the game with a double off the wall in right and later scored on Jarred Kelenic’s fielder’s choice.

Ford “created” another run in the second inning. He led off with a single to right, advanced to third on Eugenio Suarez’s double and “raced” home on a Winn pitched that went off the glove of Patrick Bailey for a passed ball to make it 2-0.

Ford made it 3-0 with a solo homer in the third inning.