The Mets' Jose Reyes celebrates with Dominic Smith after scoring...

The Mets' Jose Reyes celebrates with Dominic Smith after scoring a run during the first inning against the Astros on Sunday, Sept. 3, 2017, in Houston. Credit: Getty Images / Bob Levey

HOUSTON — Baseball, at its core, is an extended fraternity. When a player with potential reaches the majors, the league knows it. So Mets rookie Dominic Smith has been making the most out of every conversation he has while manning first base.

After the Mets’ 8-6 loss to the Astros on Sunday, Smith relayed one such recent chat with Astros slugger George Springer.

“He was just saying the one thing you should always take with you is to just continue to learn, no matter how many years you have,” said Smith, who has shown signs of emerging from a slow start. “Just continue to learn. Don’t focus on the results all the time.”

Smith went 2-for-5 on Sunday, including an RBI single. Though the Mets got swept in a three-game set, Smith went 5-for-13 with a homer, a double and four RBIs. For the first time since Aug. 15, he’s hitting .200.

“He’s starting to swing much, much better,” manager Terry Collins said. “I’m really pleased to see it. He’s getting the bat out and doing some damage. It’s good to see.”

Brandon Nimmo, in his first extended opportunity to play the outfield, reached base four times with a hit and three walks, one of them intentional. One of those walks came with the bases loaded to knock in a run.

Nimmo walked in every game of the Astros series. He has 20 walks in 44 games, raising his on-base percentage to .398.

Such strides may be the only consolation for the Mets. At 58-78, they have dipped to 20 games under the .500 mark, the furthest they’ve fallen away from the break-even point in the tenures of both Collins and general manager Sandy Alderson. Not since 2009 have such depths found the Mets, who are tied for the fifth-most losses in all of baseball.

Development is the only remaining goal, though even that hasn’t come with some complications.

Rookie shortstop Amed Rosario was pulled from the game in the eighth inning with a bruised right index finger. He had felt the issue during a swing in the second game of Saturday’s doubleheader and the finger swelled on Sunday, keeping him from gripping the bat. It’s unclear how long he’ll be out.

“We’re going to keep an eye on it, day to day,” Rosario said through an interpreter.

The Mets’ 4-1 lead disappeared in the third, when the Astros blitzed righthander Chris Flexen for five runs.

Flexen, 23, made the leap straight from Double-A Binghamton to the big leagues, and his eight starts with the Mets have underscored the scope of such a jump. He allowed towering home runs by Cameron Maybin and Springer.

“I tried to pitch to contact today and I got burned,” said Flexen, who has surrendered 14 runs in 8 2⁄3 innings in his last two starts.

Flexen’s ERA has risen to 7.85, but Collins showed no signs of taking Flexen out of the starting rotation, a nod to the Mets’ new mission of development.

Said Collins: “You’ve got to go pitch and you’ve got to learn how to deal with it.”