Alonso hits walk-off homer as A’s win Sean Manaea’s debut

Sean Manaea has a cool demeanor and seems to enjoy every moment he’s in a baseball uniform. He’s 6-foot-5 and 245 pounds but as playful and giddy as a puppy.

Then he takes the mound. The big smile is wiped away, the big hair is tucked under his cap and the big fastball is on display, along with a slider and changeup that set him apart as one of baseball’s elite pitching prospects.

Manaea made his major-league debut Friday night, but he had second billing to Yonder Alonso, who delivered his biggest hit as an Athletic, a walk-off three-run homer that gave the A’s a 7-4 victory over the Astros.

“That was a really awesome way to get welcomed to the bigs,” said Manaea, who saw the game-winner from the dugout. “That was an unreal experience.”

It was Alonso’s first A’s homer and first career walk-off homer, and he was rewarded with his first pie in the face and Gatorade shower, an A’s tradition he didn’t appear to mind.

Alonso walked to the plate hitting .162 and had made an impression only on defense. No longer. Stephen Vogt opened the ninth with a double to left-center, and Tyler Ladendorf pinch-ran and was sacrificed to third by pinch-hitter Mark Canha.

Coco Crisp was walked intentionally, and Alonso homered off sidewinder Pat Neshek, sending the ball deep over the right-field wall.

“Incredible,” Alonso said. “You don't feel anything. You're flying around the bases and, to be honest, you’re getting goose bumps. You just want to take it all in. A walk-off, just speechless.”

Manaea pitched into the sixth inning without showing enough of his best stuff and was charged with four runs on four hits and four walks. His fastball touched 94 mph, and he continued to challenge hitters with it, but not always with good command.

“It could have gone a little better. I was kind of disappointed in the end,” said Manaea, who had more than 20 relatives and friends in attendance (including his parents and girlfriend), mostly from Indiana, where he was grew up and attended Indiana State.

Manaea entered the sixth with a 2-1 lead thanks to Crisp’s two-run homer, but quickly lost his momentum. Manaea hit George Springer, walked Carlos Correa and gave up Evan Gattis’ single, which tied the game.

Manaea was pulled, and both of Sean Doolittle’s inherited runners scored, making it 4-2. The A’s tied it in the eighth on Marcus Semien’s homer and Jed Lowrie’s sacrifice fly, which scored Billy Burns, who singled, stole second and took third on a throwing error.

Burns, the center fielder, struck again in the ninth when he threw out Carlos Gomez, who was trying to stretch a double into a triple. Burns hustled to back up Crisp when Gomez hit a ball high off the left-field wall, just missing a home run, and he made a perfect throw to the bag.

Manaea’s debut overshadowed the news of two other A’s starters. Chris Bassitt went on the disabled list with an elbow strain, and Jesse Hahn was called up from Triple-A Nashville to start Saturday.

The rotation has Rich Hill on Sunday followed by Kendall Graveman and Sonny Gray, who’ll get an extra day’s rest.

Bassitt said he felt something in the elbow from spring training, thinking it might have been ordinary soreness that would go away. It didn’t. After surrendering 13 runs in his past two starts, he informed the A’s of his problem and had an MRI. Bassitt was examined and, according to manager Bob Melvin, will get a second opinion.

“I couldn’t do anything,” Bassitt said of Thursday’s outing in Detroit, where his velocity fell. “I literally cannot throw offspeed. My curveball was nothing. My slider was straight. My best pitch was my changeup.”

Hahn’s poor spring (11.15 ERA) got him a ticket to Nashville, where he had a 2.04 ERA in four starts. Reliever Andrew Triggs also was called up, and Matt McBride was optioned.