Will Powers, Associated Press Diamondbacks catcher Johnny Estrada, left, watches as Jeromy Burnitz congratulates Jason Bay as he crosses the plate after hitting a home run in the first inning last night at Chase Field in Phoenix. Click photo for larger image. More Coverage: Pirates Notebook: Agent says Pirates privy to Duffy's situation Bob Smizik: Maybe it's time to blame the players Looking Ahead: Matchup: Pirates (Duke 2-5) vs. Diamondbacks (Batista 3-2) (4-2), 6:40 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 -- It would be easy to blame Ryan Doumit.

A ball was sliced right at him, it slipped under his glove, and it set the stage for three Arizona runs in the decisive fifth inning of the Pirates' 7-3 loss to the Diamondbacks last night at Chase Field.

But there is this to be considered: Doumit was playing first base for the second time in his professional career. Actually, in his life. The coaching staff began teaching him the position only three weeks ago, and he still takes daily grounders after batting practice.

There is this, too: Doumit was setting foot on the field for the first time since May 6, when his left hamstring was strained. He had been limited to pinch-hitting duty in the interim, and the trainers still did not deem him fully recovered yesterday.

So, was he at fault?

Depends upon whom you asked after the Pirates' third consecutive defeat.

Here is how the Diamondbacks took the fifth:

With the score tied at 2-2, Pirates starter Victor Santos put down the first two hitters before walking Chad Tracy. Luis Gonzalez followed with a grounder toward Doumit, but it eluded the glove and continued into right field, pushing Tracy to third.

Conor Jackson, next man up, launched a 2-0 Santos changeup to left for a three-run home run and a 5-2 Arizona lead that would never be challenged.

Pirates manager Jim Tracy, who before the game described Doumit as "healthy enough" and put him into the lineup in hopes of some left-handed pop, did not excuse the error.

"That's some of the chance that you take when you're trying to influx your lineup with a little more offense," Tracy said. "The ball wasn't really hit all that hard. It's a makeable play. That's not one of Luis Gonzalez's better swings that he took. It's a makeable play. That's all I have to say about it."

Two of Doumit's infield mates viewed the play differently.

"It was a line-drive smoked right at Ryan, and he was holding a man on first. I mean, dude, that's a hard play to make," shortstop Jack Wilson said. "You just hope it doesn't discourage him because he's worked so hard to do well at first base because he knows we need him in the lineup. You feel for him."

"That was a hard hit," third baseman Freddy Sanchez said. "The ball got by him, but that's a tough play for anybody. The same thing could have happened to me if it was hit my way."

The other clubhouse seemed to see it that way, too.

Gonzalez told reporters afterward -- adamantly and repeatedly -- that he hit the ball with enough force that he was angry the official scorer did not rule it a hit rather than an error on Doumit.

Doumit was not immediately available for comment.

The Pirates fell to 14-32 while squandering two more home runs by Jason Bay, whose current tear includes six long balls in the past six games and a .367 average in the past 15.

His first shot, a Claudio Vargas fastball lifted into the left-field seats, followed Nate McLouth's leadoff double and resultant run to put the Pirates ahead, 2-0, in the first inning.

Santos gave up the lead in the fourth. Jackson walked, and Johnny Estrada got under a full-count fastball and sent it over the right-field fence to tie the score.

But Santos was kicking himself most for the Jackson home run after the Doumit error.

"Right down the middle," he said. "Bad pitch."

Tracy offered a similar assessment of that pitch, but he sounded more troubled by what preceded it that inning.

"Obviously, when they score three runs, it's a case of allowing the extra hitter to come to the plate," Tracy said. "The reality of the situation is that he shouldn't have come up."

Santos, without a victory since April 9, fell to 1-5 after being charged with two of the five runs he allowed in six innings.

Bay trimmed Arizona's lead to 5-3 in the eighth with his second shot, a 418-foot blast to center off a fastball from reliever Brandon Lyon. He has 12 home runs for the season.

"Bay provided our offense," Tracy said. "He's swinging the bat very, very well. But he needs some help."

An erratic eighth -- lowlighted by one run scoring on a throwing error by Wilson and another on a wild pitch by Matt Capps, each after two outs -- let Arizona pull ahead, 7-3.

The Pirates committed three errors for a total of five in the first two games of this series. They arrived here with a 90-inning errorless streak.