OAKLAND -- The A’s were hopeful that Chris Bassitt would seamlessly return to his ace-like form. In reality, though, nobody truly knew what to expect on Thursday afternoon.

Only 37 days had passed since Bassitt’s season was put in serious jeopardy on Aug. 17, when he was hospitalized after being struck in the face by a 100.1 mph liner off the bat of Brian Goodwin during a game against the White Sox. Prior to that horrific incident, the 32-year-old right-hander was steadily building a serious case for American League Cy Young consideration, ranking among the league leaders in most pitching categories by going 12-4 with a 3.22 ERA and 154 strikeouts in 151 innings across 25 starts.

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So when Bassitt triumphantly returned for his first start at the Coliseum since that devastating injury in August, his inspiring presence provided the A’s with a spark they desperately sought. Looking like his All-Star self for three scoreless innings against the Mariners, Bassitt was backed by his offense with three early runs. But that jolt of positive momentum was short-lived.

On a strict 50-pitch count, Bassitt departed after completing three innings at 48 pitches. Once he left, the A’s fell back into the same issues that have pushed them further and further away from a playoff spot, with the bullpen squandering a three-run lead to take a 6-5 loss to Seattle.

It was a game manager Bob Melvin declared as one the A’s “have to win” after dropping the first three games of the series against the Mariners (84-69). Instead, Oakland (82-71) was swept over four games by the team directly ahead of it in the American League Wild Card standings, sinking to four games back of the Yankees (86-67) for the second Wild Card spot with only nine games left in the regular season.

“Very disappointing,” Melvin said. “Four-game sweeps are tough to do. We’re at home and we have a lot to play for. They got big hits when they had to. [They're] a team that doesn’t score a ton of runs. You’d think when you score five, you have a chance to win this game.”

After Bassitt’s exit, a Mariners offense that was silent early stormed back against rookie James Kaprielian, who took over in the fourth. By the time the top of the sixth came to an end, Kaprielian and left-hander Jake Diekman had been tagged for six runs on five hits (three homers) over just 2 1/3 innings, with Diekman giving up both a game-tying solo blast to Mitch Haniger and a go-ahead two-run homer to Luis Torrens in the sixth. What was once a 3-0 lead quickly flipped into a 6-4 deficit.

“The pitch to Torrens, I didn’t think was a bad pitch,” Melvin said. “Pitch to Haniger was maybe away and higher than he wanted. Two long balls got him right there.”

Bullpen struggles continue to be a signature flaw in Oakland’s recent free fall down the standings. Over the past 30 games, A’s relievers have posted a 5.70 ERA with 11 blown saves. Their 28 blown saves for the season ranks as the second most in the AL.

Aside from Matt Olson adding to his stellar offensive numbers this season with his 38th home run -- a solo shot off Paul Sewald in the ninth -- the A’s once again went down without much of a fight as they were limited to two hits over the game’s final five innings.

Mathematically still alive in the race for a postseason berth, these A’s maintain their drive to fight until the very end. At the same time, they remain realistic about their grave state of playoff contention, which has only worsened with each day that has gone by this week.

“We are so far behind the 8-ball right now in the standings that it’s tough to look at,” Bassitt said. “Obviously, the last month has been terrible for us.”

Bassitt had the A’s set up for a welcomed feel-good win. Of his 11 batters, he retired the final nine in a row, including four via strikeout. Even Bassitt’s loopy curveball returned in vintage form, using it as the putaway pitch to create off-balance swing-throughs on strikeouts of Jake Fraley and Ty France.

This could have been a story about the A’s, who went 14-19 in Bassitt’s absence, getting one final emotional boost for the last stretch of the season. Regardless of the outcome, though, one thing did hold true: Bassitt got his redemption.

“It is what it is,” Bassitt said. “I’m proud to be an Oakland A. I’m proud of this group, even though we have absolutely sucked the last month. It is what is. We haven’t done a good enough job to win games. But I’m still happy as hell to be a part of this group.”