Loss to Pirates stalls Dodgers’ momentum as Don Mattingly weighs roster decisions

The Dodgers’ magic number for winning the National League West remained unchanged at seven with 14 games to play following Sunday’s 4-3 loss to the Pittsburgh Pirates in a sweltering Dodger Stadium matinee.

But as time runs out on a pennant race that long ago lost its drama, Dodgers Manager Don Mattingly will soon begin turning his attention to another magic number: 25.

That’s the number of players the Dodgers can carry on their postseason roster. And with two weeks remaining in the regular season, Mattingly faces a number of tough decisions to get down to that limit.

Among those still auditioning are infielder Corey Seager and right-hander Mike Bolsinger, neither of whom was in the majors at the end of August. And on Sunday, Seager moved closer to a spot on the playoff roster while Bolsinger did little to help his case.

Seager, who has failed to reach base in just one of his 16 big league games, went one for four with a double Sunday and made a splendid defensive play to start a rally-killing double play. And with regular infielders Jimmy Rollins (finger) and Justin Turner (knee) battling injuries, he looks like a lock for October.

“I never thought about it. It was never even a glimmer of thought,” Seager said of his postseason plans just three weeks ago. “So either way it’s not going to be disappointing.”

But it will be for Bolsinger, who was 5-3 with a 2.83 earned-run average when he was pushed back to the minors by the trade-deadline deal that brought Alex Wood and Mat Latos to the team in July. Since his return earlier this month, the right-hander has failed to get past the fifth inning in three starts, posting a 6.23 ERA.

“If I go out there and do what I’ve been doing, I’m probably not going to make the playoff roster,” confessed Bolsinger, who said he’s lost the feel for his off-speed pitches. “But if I go out there and pitch like I was and really get back into things, I know I’m going to put myself in a good position to get to a good place.”

Bolsinger showed glimpses of that Sunday despite being blistered by 97-degree heat and a second-inning line drive off his wrist that led to an unearned run.

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But he was really stung by the long ball, hanging curveballs to Starling Marte and Pedro Alvarez, who hammered them for homers. Marte’s 17th of the season, which came in the third, erased the Dodgers’ second one-run lead of the game. Alvarez’s 25th homer of the year came an inning later and gave Pittsburgh the lead for good.

Mattingly also faces some tough roster decisions in the outfield, where time is running out for Yasiel Puig. He is far from running at full speed because of a hamstring strain and that could open a spot for Justin Ruggiano, who is hitting .342 in 13 games since being acquired from Seattle.

“Honestly, I don’t really think about that,” said Ruggiano, who has played for five teams in seven years but has never appeared in a playoff game. “I just think about the day-to-day process of what we have to do and get ready to play.”

Mattingly insisted he’s following the same approach — at least until the Dodgers officially clinch a playoff berth.

“We haven’t got to thinking like that yet,” Mattingly said of the postseason. “We’re still trying to win games. So once we get there, we’ll be talking about that.”

Up next

Left-hander Brett Anderson (9-8, 3.35 ERA), pitching on an extra day’s rest, will face Arizona right-hander Jhoulys Chacin (0-1, 2.95) Monday in the opener of a four-game series against the Diamondbacks. TV: SportsNet LA; Radio: 570, 1020.

kevin.baxter@latimes.com

Times correspondent Steve Dilbeck contributed to this report.

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