John Lackey had a simple explanation for his recent resurgence.

“I’m healthy,” Lackey said after pitching eight strong innings for Boston in a 4-1 win over the San Diego Padres on Tuesday night. “I’ve been locating the ball pretty good, but it has happened before, you know.”

Not this frequently, and not recently.

Lackey (6-5) won his fourth straight decision and has a winning record for the first time since late in 2011. He missed all of last season recovering from Tommy John surgery and after an early scare in April appears to be throwing the way he did a few years ago when he was one of the top pitchers in the American League.

Lackey struck out six and scattered six hits while walking just one. The only run he allowed was a solo homer by Jesus Guzman in the seventh.

“He’s been a good pitcher for a long time,” Boston catcher Jarrod Saltalamacchia said. “It’s just a matter of being healthy, having a feel, having the velocity back. And that’s what he’s doing.”

Boston fans, who repeatedly booed Lackey as he struggled through injuries two years ago, cheered him as he left the mound after the top of the eighth.

“I’m just having a good time pitching,” Lackey said. “I’m not really worried about what slack I need to pick up or any of that. I missed a full season. I’m enjoying feeling good and enjoying competing.”

Koji Uehara replaced Lackey in the ninth and struck out two, earning his fifth save for the Red Sox, who improved to 6-1 during a nine-game homestand.

The Padres have lost four straight and six of seven.

San Diego rookie Robbie Erlin (1-1) threw 93 pitches over 3.2 innings before getting pulled after Brandon Snyder’s bases-clearing double in the third put Boston up 3-0.

“He had to work for every out he had. It drove his pitchcount up,” manager Bud Black said. “The ball off the wall with the bases loaded was the backbreaker. But Robbie competed. For a young pitcher coming in here, he didn’t back down, didn’t scare off, went at them.”

Lackey last had a winning record at 12-11 in late 2011, when he finished the season 12-12 and missed all of last year recovering from surgery. He needed only six pitches to get out of the sixth inning before Guzman spoiled the shutout bid in the seventh with a shot off the top of the Green Monster in left. The umpires held up Guzman at second briefly before conferring and ruling it was a homer without going to video replay.

Boston fans booed the call, but replays showed it was correct.

David Ortiz hit his 500th career double in the first and Jose Iglesias added an RBI single in the sixth for Boston.

Erlin was solid through the first three innings, but could not get himself out of trouble in the fourth. Ortiz led off with a single and Mike Napoli followed with a walk. After striking out Jonny Gomes for the first out, Erlin walked Saltalamacchia to load the bases for Snyder.

Snyder forced Erlin to throw nine pitches, fouling off five before hitting a double off the upper right corner of the Green Monster — just a few feet more to the right and it would have been a grand slam. Snyder was thrown out trying to stretch out a triple, which would have left Erlin liable for another possible run.

Erlin was done for the night after Snyder tagged his 93rd pitch.

Notes — The fifth all-time series between the Padres and Red Sox continues tonight with RHP Edinson Volquez (6- 6) starting for San Diego against Jon Lester (8-4). … Ortiz became the 58th major leaguer to hit 500 doubles and the fifth active player to do so. … Snyder was called up from Triple-A Pawtucket the week before and had two RBIs entering the game. … Center fielder Jacoby Ellsbury extended his hitting streak to 12 games. … Pedroia has reached base safely in 43 of 45 home games this season. … San Diego shortstop Pedro Ciriaco returned to Fenway Park for the first time since being acquired by the Padres on June 14 for cash and got a quiet but warm round of applause in his first at-bat.