PITTSBURGH -- To say that Luis Severino entered the season with something to prove would be putting it mildly.

Severino’s stuff was never in question. His ability to stay healthy, however, very much was. At the halfway point in the regular season, it’s been so far, so good for the 30-year-old right-hander who has, at least for now, quieted concerns over his health while offering Mets fans plenty of optimism.

Despite an off night Friday in the Mets’ 14-2 series-opening loss to the Pirates at PNC Park, Severino’s argument for returning to the Midsummer Classic for the third time in his career and the first time since 2018 is still somewhat compelling.

Severino allowed a season-high seven runs on nine hits in six-plus innings of work. The right-hander began his outing efficiently, firing a 10-pitch first inning and needing just 38 pitches to get through the first three frames, but eventually, the hard-hit balls that were once finding his fielders’ gloves began landing in the gaps. And the seats.

After allowing just nine home runs across his first 16 starts of the season, Severino allowed a season-high three to Pittsburgh. In the fourth inning, Rowdy Tellez and Jack Suwinski each drove solo home runs on pitches left over the plate into the right field seats. Then, in the fifth, with a runner at second base, Bryan Reynolds blasted the Pirates’ third home run of the game, putting the Pirates ahead for the first time on the night.

Severino’s outing ended before he could record an out in the seventh inning, after he allowed a leadoff double to Yasmani Grandal, a single to Michael A. Taylor and a walk to Joshua Palacios. Five pitches later, Reynolds hit his second home run of the game – a grand slam off reliever Jake Diekman -- to put the game well out of reach. The Mets’ bullpen allowed three more home runs, totalling seven afforded on the night, which tied the franchise record for most allowed in a game.

“I don't think the [secondary pitches] were not working. I just wasn't throwing them enough,” Severino said. “To the righties, I was attacking with my slider and sinker, and to the lefties it was just sinkers and sinkers. I just need to trust my pitches and command my pitches better.”

After signing a one-year, $13 million contract with the Mets in December, Severino has, for the most part, been a stopper at the top of New York’s starting rotation. The righty hasn't missed a start this season. Among Mets starters with 10 or more starts made, Severino has led the rotation in innings pitched (103 1/3) and WHIP (1.20), and his 3.83 ERA trails only Sean Manaea (3.67). He's also held opposing batters to a .234 batting average.

Severino’s health thus far is much better than it was at any point during the past few seasons.

Severino missed most of the 2019 season due to rotator cuff inflammation before losing the entire ‘20 season after undergoing Tommy John surgery in February. Severino was then limited to just 18 starts last season due to a lat strain. Friday’s outing gave him the most innings he’s thrown in a season since 2018, when he was a member of the Yankees.

Still equipped with the same mid-to-high 90s fastball that turned him into one of the most dominant young arms in the American League, one reason for Severino’s career resurgence has been the increase in his usage of a sinker. The righty has turned to the once-seldom-used pitch to retire opposing bats at an impressive rate.

Severino’s usage rate on his sinker has increased by 25% this season, which has led to a 50.3 ground-ball rate, placing him in the 82nd percentile, per Statcast -- his highest mark since 2017.

Severino went away from his secondary pitches in Friday’s loss, and he was hit much harder as a result. But his season so far speaks for itself.

“Today was one [of those days], but he's been doing a really good job,” manager Carlos Mendoza said. “They were aggressive and a lot of pitches [were left] over the plate.”