Dodgers’ bullpen lets one get away in Chicago

On a day Adrian Gonzalez belted a couple of home runs and drove in five runs to become baseball’s leader in runs batted in, the Dodgers couldn’t win.

The 8-7 defeat Saturday to the last-place Chicago Cubs was crushing, not only because of how or when it happened, but also because it exposed a weakness that could compromise the Dodgers’ World Series ambitions.

Entrusted to protect a five-run lead for three innings, their setup men failed. J.P. Howell gave up a three-run home run in the seventh inning, Brian Wilson served up a two-run shot in the eighth and the Dodgers were forced to listen to the fans at Wrigley Field sing along to the Cubs’ seldom-played victory anthem.

The Dodgers’ magic number to win the National League West was reduced to five, but only because the second-place San Francisco Giants dropped their second consecutive game to the San Diego Padres.

The same bullpen that failed Saturday will be responsible for pitching the entire game of the series finale Sunday.

With Hyun-Jin Ryu sidelined by shoulder inflammation, the Dodgers pushed back Dan Haren’s start from Sunday to Monday for the opening game of a critical three-game series against the Giants at Dodger Stadium.

Jamey Wright will start Sunday and will be followed by a parade of his fellow relievers.

Wright, 39, smiled when asked how long he thought he could pitch.

“I’m going to take it one pitch at a time, go as long as I can, as deep as I can,” Wright said.

Manager Don Mattingly maintained a calm facade. He pointed to how the Dodgers were able to get the ball to Howell with a five-run lead even though Roberto Hernandez’s start lasted only four innings.

“We got the ball to the guys we wanted to have the ball,” Mattingly said.

Mattingly said he doesn’t plan to reassign roles in the bullpen, meaning Howell, Wilson and Brandon League will continue to set up for closer Kenley Jansen.

Howell has pitched well this season, but his workload has raised concerns. He pitched in 61 of the Dodgers’ first 136 games.

Conscious of that, Mattingly has used him only five times this month. His appearance Friday was his first in nine days, but that didn’t go well, as he was charged with two runs and three hits in one inning.

Saturday was worse.

Inheriting a 7-2 advantage, Howell gave up three hits, walked a batter and threw a wild pitch. He gave up four runs in the inning, the last three on a home run by Arismendy Alcantara that reduced the Dodgers’ lead to 7-6.

“I was bad and they were good,” Howell said.

Howell refused to blame his workload, noting his recent nine-day break.

As for Wilson, he continued his season-long trend of throwing pitches with underwhelming velocity. None of the 16 pitches he threw in the eighth inning were clocked faster than 88 mph.

His 1-2 pitch to Chris Coghlan landed in the right-field stands for a two-run home run that completed the collapse. It was the second homer of the game for Coghlan, who went four for four.

“It’s all my fault,” Wilson said.

Wilson said he wasn’t concerned about his velocity, saying he is more focused on movement and location than he is on radar gun readings. He said he threw mostly cut fastballs and claimed he could throw a pitch in the mid-90s whenever he wants.

Wilson tried to downplay the significance of the defeat by highlighting what went right for the Dodgers, in particular Gonzalez’s performance.

Gonzalez’s two-run home run in the first inning and three-run blast in the third raised his season RBI total to 111, the most in the majors.

Gonzalez, who has never won an RBI title, has been particularly dangerous since the All-Star break, batting .324 with 11 home runs and 51 RBIs in 58 games.

dylan.hernandez@latimes.com

Follow Dylan Hernandez on Twitter @dylanohernandez