Carlos Mendoza can find something positive to say about how a sewer smells. He can look at rags and see riches. He is a man who reacts to crisis and despair with positivity and resolve.

So how he looked and sounded after Friday night’s loss — of a game to the Yankees and, more dramatically, of Clay Holmes for a while — was stark. With all the down moments of his two-plus years managing the Mets, Mendoza had never exhibited gloom and resignation like this — a boxer taking one body blow too many.

“We felt it. Not going to lie: Last night was tough,” Mendoza said before the middle game against the Yankees. “We’ve been hit this year with a lot of our superstars, with a lot of key players. But yesterday felt different.”

That was because Holmes, lost to a fractured fibula, has not only been the best Met within this disappointing quarter season, but he also represented a key to the most fathomable way for the team to fight back toward .500 and contention. Holmes, Nolan McLean and Freddy Peralta comprise a rotation Big Three that provided a conceivable pathway to, say, the kind of 15 wins in a 20-game surge needed to revive playoff possibilities.