SEATTLE -- Their defense has been spotty. Their bullpen is suspect. Their rotation lacks a dominant ace. But when your offense is averaging eight runs per game, turns out a lot of shortcomings get covered up.

So it is that the Mariners find themselves off to their best start in 24 years after pounding out a 10-8 win over the Red Sox on Sunday at T-Mobile Park, taking three of four games from the reigning World Series champs and improving to 5-1 on the season.

“What a series,” said manager Scott Servais. “It was an unbelievable series by our offense. We got big hits. We hit homers. It was really fun to watch. The confidence is really growing among all the guys in the lineup, no matter where we put ‘em. Everybody is contributing, and that’s what it takes to put up big numbers against a team like that.”

The Mariners had to survive a ninth inning in which Cory Gearrin and Chasen Bradford walked four batters to force in a run before Bradford struck out Christian Vasquez and got a groundout from Jackie Bradley Jr. to record his first career save.

“I couldn’t breathe there for a minute, but it was awesome, just helping this team win,” said Bradford after making his first outing of the season a memorable one. “It wasn’t the easiest of situations, but that’s part of the game, coming in when you have to come in.”

It’s just the fourth time in franchise history the Mariners have started 5-1 or better, having gone 6-0 in 1985 and 5-1 in ‘84 and ‘95, and they’re doing it with a club that traded away All-Stars Robinson Cano, Jean Segura, James Paxton and Edwin Diaz and let Nelson Cruz walk in free agency.

The rebuilding Mariners mashed 28 hits and 28 runs (22 earned) in 15 innings off the vaunted Red Sox rotation of Chris Sale, Nathan Eovaldi, Eduardo Rodriguez and Sunday starter Rick Porcello, who departed after 2 2/3 innings with a 9-3 deficit.

Catcher Omar Narváez’s three-run blast highlighted a seven-run third inning, and Jay Bruce added a solo shot in the fourth as the Mariners hiked their homer total to 15 for the season and 11 for the four-game series.

Seattle outscored the Red Sox by 10 runs (34-24) in the series and has put up 48 runs in 54 innings on the season, which started with a two-game sweep of the A’s in Tokyo on March 20-21.

The 34 runs allowed by Boston ties the most given up in the first four games of a season by a defending World Series champion -- a mark set by the Orioles in 1984 -- and the 11 homers are the most allowed by a defending champ in its first four games.

Dee Gordon had two hits and three RBIs from his ninth spot in the order and third baseman Ryon Healy went 2-for-4 with a double and has an extra-base hit in each of the Mariners’ first six games. The club record for most consecutive games with an extra-base hit to open a season is seven by Ken Griffey Jr. in 1997, and the MLB record since '08 is eight by Sandy Alomar in '97 and Alex Rodriguez in 2007.

As for the defense? An error by Healy allowed two unearned runs in the first off Wade LeBlanc, who pitched better than his final line of seven hits and six runs (four earned) allowed over 5 1/3 innings. But the 34-year-old southpaw wasn’t about to complain after being spotted a six-run lead in the first three frames.

“These boys can hit,” LeBlanc said. “You just want to get as many outs as you can and let them get back in the dugout and swing it.”

And the bullpen got a big boost with 1 2/3 scoreless innings from rookie Matt Festa, who been strong in three outings now, along with a big out from Roenis Elias to get out of a two-on jam in the eighth and Bradford’s high-wire save as the Mariners begin piecing things together with closer Hunter Strickland expected to miss significant time with a strained lat.

“We’re going to pick up each other, as we’ve always done here, including last year,” Bradford said. “When guys struggle, other guys pick ‘em up. It sucks to lose [Strickland] because he is a big part and a fantastic human being besides that, but we’re going to pick him up and keep going.”

Add it all together and while the long-term picture clearly has questions, the short-term sees the Mariners sitting at 5-1 and being just one ninth-inning meltdown from sweeping a four-game series against the defending champs.

“We’re coming together as a ballclub,” said Servais, “and it’s a great way to start the season at home.”