Roy Dabner, Associated Press Pirates' Oliver Perez follows through on a pitch in the third inning of last night's loss to the Diamondbacks, 4-3. Click photo for larger image. More Coverage: Pirates Notebook: Duffy's absence stems from unhappiness with game Stats Geek: Pirates are bad, but this ex-Pirates team is even worse Ron Cook: Pirates should take the lead and help Duffy solve his problems Looking Ahead: Matchup: Pirates (Victor Santos 1-4) vs. Claudio Vargas (4-2), 9:40 p.m. Where: Chase Field, Phoenix. TV/radio: FSN Pittsburgh/KDKA-AM (1020) and Pirates Radio Network. Game Statistics Provided by Forecaster Pirates vs. Diamondbacks box score Game play-by-play

PHOENIX -- Oliver Perez pitched as well as he had in more than a year, but these do-just-enough-to-lose Pirates fell apart in the field and fell short at the plate, 4-3, to the Arizona Diamondbacks last night at Chase Field.

"Simply put, we got beat due to not executing the little things that make you a good team," manager Jim Tracy said.

Perez lasted six scoreless innings and allowed four hits and three walks while striking out four. That marked the first time he prevented an opponent from scoring since April 25, 2005, when he blanked the Houston Astros through 8 2/3 innings at PNC Park.

"Tremendous outing," Tracy said.

But unusually porous defense after Perez's exit kept him from recording victories in back-to-back starts for the first time since last June.

Jason Bay's home run to lead off the second against Arizona starter Orlando "El Duque" Hernandez accounted for the only scoring of the first 6 1/2 innings. Bay waited out a dangling first-pitch curve and drilled it inside the left foul pole for his 10th home run, his fourth in the past five games.

Damaso Marte relieved Perez to start the seventh and walked pinch-hitter Andy Green. Two outs later, Green was on third, then sprinted home when Luis Gonzalez bunted up the third-base line after seeing Freddy Sanchez playing deep.

Sanchez gloved the ball in time to get Gonzalez, but he bobbled the exchange for what was ruled an infield single, and the score was tied at 1-1.

"It was going to be a tough play," Sanchez said. "But I felt I had him."

The Pirates had a 97-inning errorless streak entering the next inning, but two more miscues gave away the game.

Marte again walked the first batter, Shawn Green, then allowed Damion Easley's single. The runners were bunted over, and Orlando Hudson lifted a soft shot toward the line in right. Jeromy Burnitz was there in time but, accelerating his transfer for a throw home, allowed the ball to clank off his underhanded glove.

Green scored for a 2-1 lead.

"I was probably trying to rush," Burnitz said. "Obviously, looking back, I should have just gotten under it to catch it. Just catch it. I had no chance at that runner."

Tracy said he felt it would have been "a close play" at the plate.

It would get worse.

After Marte struck out pinch-hitter Tony Clark, Craig Counsell rolled a squibber to the left of the mound, but Marte's throw to first sailed into right field for two more runs.

All of which would come back to bite the Pirates when they nearly tied it in the ninth.

They loaded the bases off Diamondbacks closer Jose Valverde with nobody out and, after Ronny Paulino popped out, Jose Castillo drove in two with a single up the middle. But pinch-hitter Jose Hernandez struck out swinging to drop his average to .146, and Nate McLouth lined out to left.

The Pirates are 4-13 in one-run games, worst in Major League Baseball.

Asked about the uncharacteristic defense, Tracy raised the subject of close defeats instead.

"It's another one-run loss," he replied. "We've had 17 one-run games by the 22nd of May and ... the little things are very important. We walked the leadoff man in the seventh and eighth. We dropped a fly ball. We didn't get the extra hit we needed."

Perez left the bases loaded in the first and allowed a baserunner in four of the next five innings, but never more than one at a time.

By his final two innings, his velocity had ratcheted up to 94 mph, continuing a recent trend of increasing as the game goes. And, perhaps most intriguing, he seemed to show confidence in a dramatic left-to-right slider that reminded of his 2004 form.

Tracy credited the work of pitching coach Jim Colborn for stabilizing Perez's delivery in the two starts since his turn was skipped in the rotation.

"There's a real understanding there," Tracy said. "He never lost his delivery, never lost his command. There was one pitch that was badly thrown all night."

That came when Perez hit Conor Jackson in the first inning.

Tracy explained that he batted for Perez in the seventh in part because his pitch count was at 97, but mostly because he wanted Ryan Doumit to face Orlando Hernandez with men on first and second and two outs. Doumit popped out.

Perez seemed buoyed by the performance.

"Everything's getting better," he said. "My velocity is consistent, and I have my slider going. I think we're doing a great job. I just want to get better and better."

The Pirates are 14-31, but Tracy spoke -- for the first time this season -- about diminishing the importance of the team's place in the standings.

"We're making strides," he said. "We have to not involve ourselves with our won-lost record, but with staying with a process. We have to keep putting ourselves in position to win games. Those are going to go our way, eventually."