Sanchez has a .324 average with nine home runs and 34 RBI vs. New York, matching or topping his bests against any NL team. He lost playing time after Davis was acquired in a trade with the Mets in mid-April.
"Ike's a good player and he's been swinging the bat really well. He's been one of the hottest bats on the team. So, he's going to play and I understand that," Sanchez said about Davis, who was making his return to Citi Field. "My role is to keep that going whenever I get my chance, keep that going and help the team win."
The Mets announced after their ninth loss in 12 games that they had fired hitting coach Dave Hudgens. New York also cut reliever Jose Valverde soon after he gave up Sanchez's go-ahead hit.
Valverde (1-1) was booed off the field after allowing pinch-hitter Jose Tabata's tying single in the eighth. Valverde returned for the ninth and was even worse, yielding four runs overall.
"Don't think for one second that there's not a guy in there that realizes that this is part of it. We just released one of the best professionals I ever been around in Jose Valverde," a fired-up Collins said. "You deal with it, and if you can't you don't belong in the game."
Mets minor league hitting coordinator Lamar Johnson will take Hudgens' place. Right-hander Vic Black is being recalled from Triple-A Las Vegas to fill Valverde's spot.
Sanchez fouled off a fastball, losing hold of the bat, which spun toward the Pirates dugout and hit a batboy in the legs. The batboy smiled and on-deck hitter Russell Martin checked to see if he was OK.
Sanchez then singled to left, scoring Walker. Juan Centeno couldn't handle Curtis Granderson's throw that bounced to the right of the plate and skittered past Valverde, who was backing up but way too close to the catcher. McCutchen scored on Granderson's error for a two-run lead.
Martin added an RBI double for Pittsburgh, which rebounded from a loss to Washington on Sunday after a season-high four straight wins.
"This mentality in the dugout is, `This is the inning.' Even if we get pushed down, the next inning we'll make something," Hurdle said. "You've got to be relentless. You can't get sad."
Tony Watson (5-0) pitched an inning for the win.
Mark Melancon got his 10th save.
Davis drew a warm reception from the Memorial Day crowd of 29,309, opposite of what he predicted during a pregame chat in the visitor's dugout. Popular with fans in his four-plus seasons, he went 0 for 2 with a walk.
Slumping Lucas Duda homered off Melancon to start the ninth. The homer was the first off Melancon in 86 innings, since April 14, 2013.
New York took a 2-0 lead in the fifth on Daniel Murphy's single, Pittsburgh's third error of the game and a favorable review under the new home plate collision rule.
But the Mets bullpen wasted a fine start by Jacob deGrom.
The 25-year-old deGrom pitched 6 2/3 scoreless innings in his third career start, allowing five hits. He labored early but settled in to throw 122 pitches.
With the help of an umpire's review, New York took the lead.
The Mets two-out rally was started by -- who else? -- deGrom. He lined a single to left field for his second hit of the day and advanced when Juan Lagares walked.
A college shortstop, deGrom is now 4 for 5 as a big-league batter.
"I guess I've been seeing the ball pretty well," deGrom said.
Murphy lined a single to right field and deGrom scored easily. Josh Harrison's throw to third skipped passed third baseman Pedro Alvarez and Lagares scampered home. The ball took a good bounce back to Alvarez off the protective fence in front of the Pirates dugout and he made a quick throw home.
Martin set up to the left of home plate but stuck his leg out, blocking Lagares' path before the ball arrived.
Umpire Laz Diaz initially called Lagares out, but Collins asked crew chief Jeff Nelson to review the play under new rule 7.13, covering collisions at the plate.
After a delay of 3 minutes, 4 seconds, Lagares was called safe and Murphy was awarded second base on the play home.
"We've encouraged our guys to play the game, do what you feel athletically moved to do knowing what the options are," Hurdle said.
The Mets placed OF Eric Young Jr. on the DL because of a right hamstring strain. They recalled OF Matt den Dekker from Triple-A Las Vegas to take his place. ... The Pirates designated RHP Vin Mazzaro for assignment to make room for Cumpton. ... Up Next: Pirates RHP Edinson Volquez (2-4) will face Mets LHP Jonathon Niese (3-3) on Tuesday night.