Adam LaRoche homered and Desmond and Denard Span had RBI doubles in a four-run second to spoil Wheeler’s home debut, which became such a laugher that catcher Anthony Recker pitched the ninth inning.
Jayson Werth also homered against the Mets’ touted rookie as Washington finally gave Gonzalez (5-3) some run support — and then some.
The Nationals set a season-high for runs as they reached the midpoint at 41-40, a disappointment for the NL East preseason favorite. Washington improved to 4-8-2 in road series by taking two of three from the Mets.
Kurt Suzuki hit a two-run homer and Anthony Rendon had a two-run double when Washington batted around in a six-run eighth. Suzuki also had an RBI single in the second against Wheeler (1-1).
A day that began with such promise for Mets fans ended as Recker smiled while while warming up to pitch the ninth. Desmond hit a two-run homer off the facade of the restaurant in left field, giving him 28 RBIs in June and a Nationals record for any month.
Gonzalez (5-3) won for only the third time in 11 outings since May 5, even though he has given up two earned runs or fewer in 10 of those games.
After giving up a one-out single to Daniel Murphy and walking David Wright in the first, Gonzalez retired 17 of 18 around Wright’s fourth-inning double before pinch-hitter Zack Lutz walked to open the seventh.
Josh Satin followed with a single, and pitching coach Steve McCatty took a slow walk to the mound. Gonzalez retired the next three batters and finished with seven strikeouts and two walks.
Mets starters Matt Harvey and Dillon Gee dominated the Nationals in the first two games of the series, and many of the 33,366 — the second-highest attendance this season at Citi Field after opening day — were eager to see Wheeler do the same in his third big league start. The crowd included his parents and two brothers
Wheeler got the biggest cheer from fans when lineups were announced and then another roar after striking out two in the first with a fastball that ranged from 94-98 mph. But he didn’t make it through five innings.
LaRoche quieted the crowd in the second with a drive off the facing of the second deck in right field on the first pitch. Unsettled, Wheeler walked Werth on four pitches and allowed an RBI double to Desmond.
Desmond laid off two sliders before sending a fastball into the right-center gap. One long fly out later, Suzuki singled through a drawn-in infield for a 3-0 lead. After Gonzalez struck out, Span doubled to left-center on a 93 mph fastball for the inning’s final run.
Wheeler slowly walked off the mound to near silence. When Wheeler sat in the dugout, manager Terry Collins stopped by for a moment and the 23-year-old received pats of encouragement from pitching coach Dan Warthen and Harvey.
Werth homered to left-center on another fastball with two outs in the third and Wheeler was chased after walking LaRoche with two outs in the fifth, putting runners on first and third.
The sixth overall pick by San Francisco Giants in the 2009 amateur draft, Wheeler has had mixed results in the majors. He pitched six scoreless innings in his debut in Atlanta but gave up four runs and four hits in 5 1-3 innings against the Chicago White Sox, an outing in which Collins said Wheeler was tipping his pitches.
This time Wheeler yielded five runs and six hits in 4 2-3 innings. He struck out five and walked two.
John Buck hit a two-run homer in the ninth for the Mets.
NOTES: The Mets finished June 11-15, Washington was 13-13. ... Washington OF Bryce Harper (left knee bursitis) went 0 for 3 with a walk and run scored in what was likely his final rehab outing for Double-A Harrisburg on Saturday. He batted .364 (4 for 11) with a double, triple and homer in four games. ... Nationals RHP Dan Haren (shoulder inflammation) had a bullpen session for first time since going on DL last week.