Diamondbacks-Cubs Preview

The Chicago Cubs appeared poised to celebrate the 100th anniversary of Wrigley Field with a victory until their bullpen imploded against the Arizona Diamondbacks.

Given the way these teams’ relievers have fared the last two days, no lead may be safe Thursday as they conclude a four-game series.

Chicago (7-13) failed to claim its fourth win in five games despite taking a 5-2 lead into the ninth inning Wednesday. Three relievers then combined to allow five runs on three hits, two walks and an error in a 7-5 defeat.

Neither bullpen appears to be very sturdy after the Cubs separated themselves Tuesday with a four-run eighth in a 9-2 victory. Chicago has blown four saves in six opportunities while Arizona has squandered three of its nine chances.

The Cubs’ 26 blown saves in 2013 were the second-most in the NL behind Arizona’s 29, and their 75 since the start of the 2011 season are the second-most in that span behind Houston.

”That one finished not like we would have wanted, obviously,” manager Rick Renteria said Wednesday. ”It seemed like the inning kept opening up, and we weren’t able to end up in the end putting a stop to it.”

Given the inability by Edwin Jackson (1-1, 5.40 ERA) to go deep into games, the Cubs will likely have to look to their shaky bullpen again Thursday. Jackson has failed to complete six innings in three of his four starts, though he comes off just his second win in 14 outings. He allowed two runs and eight hits over 5 2-3 innings of an 8-4 victory over Cincinnati on Saturday.

Jackson was 6-10 with a 5.16 ERA in 21 starts for Arizona in 2010 before being traded to the Chicago White Sox at the deadline. He’s 1-2 with a 6.75 ERA in four games against the Diamondbacks since.

Arizona (6-18) won for just the second time in 12 games Wednesday, and perhaps general manager Kevin Towers’ sharp assessment of the club helped provide some motivation for the comeback.

"It’s a team that should be performing a lot better than they are, and it’s not like help is on its way," Towers told the Diamondbacks’ official website. "These guys are the guys who are going to have to get it done."

The Diamondbacks had totaled four runs in their last three games before Wednesday. Paul Goldschmidt has reached base in 23 of 24 games after going 2 for 5 with his ninth double. He’s 15 for 35 (.429) with 11 RBIs over his last nine contests against the Cubs.

Rookie Mike Bolsinger (0-1, 10.29) will make his second start after yielding seven runs and seven hits in four innings of an 8-6 road loss to the Los Angeles Dodgers on Saturday. Arizona decided to keep him in the rotation with former starter Trevor Cahill having some success as a reliever.

"It’s how you respond to it," Bolsinger said. "Each time I’ve been out there, I’ve kind of learned. I learned a lot from my first time out and I kind of learned a lot from this start. Hopefully I can take it on to the next one."

The right-hander gave up two runs and six hits in a three-inning relief appearance against the New York Mets in his major league debut April 14.

Goldschmidt and Miguel Montero, who collected a hit for the fifth straight game Wednesday, are each 4 for 9 off Jackson.

Arizona’s Mark Trumbo, among the major league leaders with seven homers and 19 RBIs, will be sidelined for an extended period of time because of a stress fracture in his left foot.