OAKLAND -- Friday night’s spectators at the Coliseum witnessed an increasingly uncommon sight: A starting pitcher who actually works deep into the ballgame.

Such beings are rare in this era of pitch counts, “openers” and skeptics who doubt that any man can face a batting order three times or more and survive. But Mariners left-hander Marco Gonzales maintained old-school durability, lasting seven innings as Seattle thumped the Oakland A’s, 9-2.

• Box score

Gonzales (7-6) wasn’t dominant or overpowering, just effective. He yielded seven hits, but issued only two walks. Moreover, Gonzales’ performance was no fluke. It marked the fifth time in 16 outings this year that he completed seven innings or more.

If anything, Gonzales gained strength as the game progressed. The A’s amassed five hits off him, as well as both of their runs, in the first three innings. They mustered two hits against him in his last five innings.

Gonzales largely determined his fate in the first inning, when he coaxed Chad Pinder’s double-play grounder with the bases loaded and one out.

“I thought that the biggest part of that inning was not getting out of our approach of getting ground balls,” he said, referring to ground-ball singles by Marcus Semien and Matt Chapman. Gonzales also prompted a double-play grounder from Josh Phegley that stopped a fourth-inning rally before it started.

And, of course, such plays extended the length of Gonzales’ outing.

Said Mariners manager Scott Servais, “He has multiple pitches he can throw for strikes at any point. Once he gets into a nice rhythm and gets all of [those pitches] working, that’s when he’s at his best.”

“He throws a lot of changeups and cutters,” A’s manager Bob Melvin said of Gonzales. “He wants to make you expand [the strike zone]. He doesn’t want to have to throw the ball over the plate unless he has to. We played into his hand a little bit.”

Gonzales also received ample offensive support, particularly from catcher Omar Narváez. Gonzales’ batterymate went 3-for-4 and clobbered a two-run homer in the seventh inning to contribute to the lopsided score. Mallex Smith added a two-run homer in the eighth.

Seattle has mashed 78 homers on the road this season, second in the Majors only to Minnesota’s 81.

But the Mariners succeeded without power during their biggest inning of the night, a three-run fourth. Trying to protect a 2-1 lead, Oakland starter Chris Bassitt (3-3) encountered trouble as the Mariners loaded the bases with nobody out. Daniel Vogelbach walked and Narvaez singled before Tim Beckham hit a potential double-play grounder to A’s second baseman Jurickson Profar. But shortstop Semien mishandled Profar’s short flip for an error. J.P. Crawford, fresh off the injured list, doubled home two runs. Dee Gordon added a sacrifice fly.