PHOENIX -- Seranthony Dominguez has been Gabe Kapler's most trusted weapon in a Phillies' bullpen that has been the best in baseball since July 1.
But the weapon is struggling.
Dominguez blew his second save in as many days in Monday night's 3-2 loss in 14 innings to the D-backs at Chase Field, which snapped the Phillies' winning streak at six games. Phillies right-hander Jacob Arrieta pitched splendidly for eight scoreless innings when Kapler handed the ball to Dominguez in the ninth. The rookie allowed a one-out solo home run to David Peralta to cut the Phillies' lead to one before Dominguez allowed a double to Eduardo Escobar and a single to Steven Souza Jr. to tie the game.
Peralta hit a walk-off homer to left-center field against Phillies left-hander Austin Davis in the 14th, cutting the first-place Phillies' lead in the National League East to one game over the Braves.
"I feel bad for Jake," Dominguez said through the Phillies' interpreter.

Dominguez is 1-3 with a 2.45 ERA and 12 saves in 36 appearances this season. He is a big reason the Phillies are a first-place team in the second week of August. But Dominguez also is 0-1 with a 7.11 ERA in his last seven appearances. He blew a save Sunday, when he allowed a game-tying home run to Justin Bour in the seventh inning at Citizens Bank Park.
"This is not his best. I'm not blind," Kapler said. "The reality is he's not pitching his best right now. But we are not wavering in our confidence in him whatsoever. We cannot wait to get him back out on the mound because we understand how good he is and the talent will prevail."

Dominguez is pitching out of the bullpen for the first time in his career and the workload continues to be an adjustment.
Consider for a moment that when Dominguez has at least one day of rest between appearances, he has a 0.81 ERA (three earned runs in 33 innings) with five walks and 41 strikeouts. But in nine appearances when he has pitched on no rest, he has a 9.82 ERA (eight earned runs in 7 1/3 innings) and eight walks with 11 strikeouts.
"I feel normal. I feel fine," Dominguez said about pitching on no rest. "I feel healthy, strong. Sometimes I don't get the results that I want. But I have to keep working hard to get to that."
The hope is that Dominguez makes the necessary adjustments to better handle those situations in the future because there could be multiple opportunities like that in September, when the Phillies will want to use their best relief pitcher in high-leverage situations. Remember 2007, when the Phillies pitched Brett Myers, Tom Gordon and J.C. Romero almost every day down the stretch?
They need Dominguez to be his best in those moments, too.
"The majority of the people that I've spoken with have given me some advice, which is to save my bullets," Dominguez said about remaining strong for the final weeks of the season. "Try to throw just a few pitches when I do a bullpen or when I'm throwing. And during the game, try to get guys out quick. We want to save our bullets for October and the playoffs."
MOMENTS THAT MATTERED
Needed that one: The Phillies had runners at the corners with no outs in the ninth, but Jorge Alfaro struck out swinging and pinch-hitter Andrew Knapp grounded into an inning-ending double play.
"Any time you have an opportunity to tack on an additional run or two you go for it," Kapler said. "It's a kill shot in those situations and we weren't able to scratch across and additional run."

Odubel scores Asdrubal:Asdrubal Cabrera dropped a flare into center field for a one-out single in the seventh. Odubel Herrera followed with a 107.6-mph rocket to the right-center-field wall for a triple to score Cabrera and hand the Phillies a 1-0 lead. He scored on Alfaro's sacrifice fly to make it 2-0.

SOUND SMART
Arrieta is 9-6 with a 3.11 ERA this season. He is 4-0 with a 2.28 ERA in a seven-start stretch since the end of June. He retired 13 of the final 14 batters he faced on Monday, while striking out four of the final eight.
"Losing a game just stinks, really," Arrieta said. "But two first-place teams going at it, and it's no easy task to score a couple of runs off Seranthony and the guys that came in behind him, so credit them for sticking with it."
YOU GOTTA SEE THIS
Cabrera knocked down a Jonathan Jay ground ball in the third inning. He casually scooped up the ball with his glove and shoveled the ball to Cesar Hernandez at second base for a forceout. Cabrera is playing more shortstop than originally anticipated since the Phillies acquired him July 29.

HE SAID IT
"He's a pretty resilient kid. He's pretty strong mentally. He's pretty tough across the board and I don't expect this to keep him down." -- Kapler, on Dominguez
MITEL REPLAY OF THE DAY
The Phillies won a challenge on a sacrifice bunt attempt in the third inning. D-backs pitcher Zack Godley dropped a bunt up the first-base line. Phillies catcher Alfaro picked up the ball on the run and threw to second base. It looked like Alex Avila easily beat the throw, but the replay official in New York ruled that Alfaro's throw just beat Avila to the bag and overturned the call. Instead of runners on first and second with no outs, the D-backs had a runner on first and one out. The Phillies have won 21 of 31 (67.7 percent) challenges this season.

UP NEXT
Phillies right-hander Nick Pivetta (6-9, 4.75 ERA) faces D-backs right-hander Zack Greinke (12-6, 2.96 ERA) on Tuesday night in the second game of a three-game series at Chase Field. Pivetta has a 6.42 ERA over his past 11 starts, but the Phillies believe he will be better down the stretch. He has struck out 73 and walked 17 in 54 2/3 innings in that span. First pitch is set for 9:40 p.m. ET.