Pirates bullpen lets down Mitch Keller in loss to Diamondbacks

The decision backfired almost immediately.

With the Pittsburgh Pirates up a run on Arizona, manager Derek Shelton opted to end Mitch Keller’s Saturday afternoon start at PNC Park after six innings and 84 pitches.

Turning to reliever Robert Stephenson to handle the seventh, the Diamondbacks quickly plated the game’s decisive runs when Pavin Smith hit a two-run homer to center field, leading to a 4-3 victory.

Stephenson (0-2, 3.09) absorbed the loss, and Keller (5-1, 2.44 ERA) took a no-decision. Despite the setback, the Pirates (24-21) and Milwaukee (24-21) remain tied for first in the NL Central after the Brewers lost to Tampa Bay on Saturday.

Keller had gotten into some trouble in the sixth, allowing two singles and a run, all with two outs, after hitting Josh Rojas.

Even though Keller’s last four starts featured a final pitch count in the neighborhood of 100, Shelton explained the decision to yank his ace.

“In the sixth inning there, he kind of lost his delivery a little bit,” Shelton said. “We saw the pitches starting to not have the same action. I think one of the things — as well as he’s pitched over the last two starts and even today — he hadn’t been in the stretch.

“Once he got to the stretch there, he kind of lost where his arm slot was. … That was the biggest thing, just seeing his stuff tick down.”

Leading into the sixth, Keller was having himself another strong afternoon.

Granted, he allowed a first-inning home run to Ketel Marte, but he then retired the next 16 batters before plunking Rojas in the sixth, which proved to be the start of a jam.

Keller allowed two runs, both earned, on three hits. He struck out eight and walked none.

Keller said he was prepared to stay in the game, but no conversation was had with Shelton after the manager informed Keller his day was done. Speaking after the game, Keller also mentioned some delivery-related issues with men on base.

“I hadn’t been in the stretch all game,” he said. “That was foreign territory for me there. I didn’t feel too sharp out of the stretch there.”

With Arizona leading 1-0, the Pirates loaded the bases in the third inning after a single by Austin Hedges and walks to Bryan Reynolds and Carlos Santana.

With two outs, Ke’Bryan Hayes ripped a bases-clearing triple off Arizona starter Brandon Pfaadt that hit the Clemente Wall, avoiding the outstretched body of Smith, who was unable to make a play on the ball.

But those would be the only runs the Pirates managed on the day.

After Arizona went ahead 4-3, the Pirates went down in order in the seventh and threatened in the eighth after Jack Suwinski hit a one-out double off Diamondbacks reliever Andrew Chafin.

But Suwinski was stranded, as Santana grounded out and Hayes popped out to end the inning.

A ninth-inning rally got off to a promising start when pinch-hitter Rodolfo Castro reached via a leadoff walk, but Arizona’s Miguel Castro quickly closed the door from there, striking out Ji Hwan Bae, Connor Joe and pinch-hitter Jason Delay in order.

“We had the situation in the eighth where we had a runner at second, one out and just did not execute,” Shelton said. “We cannot stand on the fact that we get the one hit, the one two-out hit, we have to continue to go and we didn’t do that today.”

The Pirates still have a shot to win their first series this month when Roansy Contreras (3-4, 4.40 ERA) starts at 1:35 p.m. Sunday in the finale.