PHOENIX -- The losing pitcher in the Mets' 11-5 defeat on Friday was Jon Niese, and for good reason. The left-hander committed a critical throwing error in a six-run second inning, allowing the D-backs to take a lead that they would never relinquish. On this night, Niese shouldered most of the blame.But along the way, the loss was pockmarked with images of Jason Bay's struggles. Losing favor with New York's fan base on a near-daily basis, Bay finished 0-for-4 with two strikeouts; his only meaningful contribution came on a dangerous catch in foul territory against the left-field wall. Bay is now 4-for-31 since returning from the disabled list and 0-for-15 since Saturday. He has begun losing playing time against right-handed pitchers, a trend that will continue until he rights himself. If he rights himself. "I should be better," Bay said. "I feel like I am better." But the results have not been better in the least. On Friday, Bay was part of a lineup that could not pick up Niese, who tied his career high by giving up eight runs in six innings. With the bases loaded and one out in the second, Niese tumbled backward while trying to throw out Willie Bloomquist on a run-scoring infield single. The speedy Bloomquist would have been safe even on a good throw, but Niese's sailed wide of first baseman Ike Davis and into right-field foul territory, allowing three runners to score and Bloomquist to reach third base with one out. "I think everybody in the ballpark, including myself, knew that I shouldn't have thrown that ball," said Niese, who bemoaned a lack of command with all five of his pitches. "But when you're in the heat of the moment, when you're out there battling, I just tried to force it when I shouldn't have. Hindsight, I wish I would have done a lot of things different." The D-backs also scored that inning on a bases-loaded walk from Henry Blanco, an RBI single from pitcher Josh Collmenter and a sacrifice fly from Aaron Hill. Then they added runs against Niese on Bloomquist's RBI single in the fourth inning and Paul Goldschmidt's run-scoring hit in the fifth. The Mets entered the bottom of the second with a lead, thanks to Davis' solo home run and Andres Torres' RBI single a half-inning earlier. After the D-backs went ahead, the Mets drew back within a run when David Wright blasted a three-run homer off Collmenter, snapping his 0-for-15 skid. But Collmenter grew stronger as the game wore on, retiring the final seven batters he faced and striking out the final four. He lasted six innings, allowing five runs on seven hits. "They were pesky all night," Collmenter said. "They had some soft hits and then they crushed a couple pitches I left out over the plate. It was frustrating, but I wanted to make sure I could get through it and really turn it over from a bad start to a so-so start." In a way, on a grander scale, that is also Bay's goal: to turn a bad season into a so-so season. And yet so many forces are working against him, not the least of which is a constant sense of urgency. Any discussion of Bay these days begins with his salary, due to how little he has justified the $66 million the Mets guaranteed him three winters ago. Disparaging Bay in other off-field matters is not necessarily fair, given his reputation as one of the hardest-working, most invested players in the Major Leagues. But at some point, Bay must produce. Paid to hit home runs, Bay has mustered just 24 of them over parts of three seasons in New York, a span of more than 1,000 plate appearances. Injuries have taken their toll, to be certain; this season alone, he has endured a fractured rib and a concussion, both the products of aggressive outfield play. "When you look at his last year and a half in baseball, so much of it has been spent hurt," manager Terry Collins said. "I'm not sure he's ever been able to get into a groove." Knowing that, the Mets collectively held their breath when Bay slammed against the left-field wall in the second inning, snaring Jason Kubel's foul fly ball that would have landed in the seats. Bay banged his right knee on the play and was sporting a sizable wrap on the joint after the game, but he emerged otherwise unscathed. He said he was fine. "Because we're so in need of offense right now and he's the right-handed hitter that we so desperately needed, the expectations for him are huge," Collins said. "As I've tried to explain to him, it's about continuing ... to work." "But it's kind of been that way for a couple of years," Bay said. "You go out there and you grind and you grind and you work and you work, and this and that. But ultimately, who cares? Who cares how hard you work? It's about getting stuff done. And trust me, nobody takes that harder than me."