Tebow has rough debut; Porcello nicked by grounder

Tim Tebow made his first rookie mistake even before stepping into the batter’s box.

The New York Mets newcomer walked behind home plate and took his practice swings near Boston’s on-deck circle.

“I didn’t know who that was back there. I thought it was the ball boy,” AL Cy Young Award winner Rick Porcello said.

The former NFL quarterback’s debut as a big leaguer didn’t go much better Wednesday.

Tebow went 0 for 3, twice looking at strike three and also grounding into a double play with the bases loaded in a spring training exhibition against the Red Sox.

The 2007 Heisman Trophy winner did safely reach when he was hit by a pitch in the right shoulder from fellow Florida alum Brian Johnson. But Tebow’s stay on base was brief — he got doubled off first on a line drive.

Tebow was set to lead off the third inning for his first at-bat. The lefty hitter emerged from the Mets’ third base dugout and crossed over to the Boston side, drifting toward the Red Sox ondeck circle and inching his way into Porcello’s view.

“I thought you walked around because you’re a left-hander. I found out you don’t do that,” Tebow said.

Porcello threw a fastball past Tebow, then got him to look at strike three. Tebow had a smile and friendly word for plate umpire Ryan Additon after getting called out.

Porcello was struck on the pitching hand by Yoenis Cespedes’ grounder in the fourth. The righty stayed in, but exited after Jay Bruce and Lucas Duda doubled.

“It’s fine right now,” Porcello said. “It happens quickly, so you’re just trying to get the sting out of it. I was able to throw a couple of pitches, and the second warmup pitch I was able to get down in the zone, and didn’t think it would affect me making pitches.”

•A’s 7, Italy 0 — A’s starter Kendall Graveman struck out three in three shutout innings. Jesse Hahn worked three innings of two-hit relief and Frankie Montas went the final two innings of the five-hit shutout. Third baseman Ryon Healy, getting a start at first, homered.

Orlando Oberto started for Italy and worked two innings and gave up a run on two hits.

• Giants 6, Puerto Rico 5 — Carlos Beltran and Angel Pagan each finished with multihit games for Puerto Rico.

Mike Morse hit a two-run homer for San Francisco, and Jeff Samardzija allowed one run through 3 2/3 innings. Chris Marrero, a former first-round pick of Washington in 2006, hit a gameending, two-run homer.