HOUSTON — A game that featured 16 combined walks, three errors and several more mental blunders, plus countless mistakes ultimately resulted in the most significant number: one more Mets defeat.

The second-longest game of the Mets’ season, at 3 hours and 32 minutes, also ranked high among their sloppiest.

The Mets had trouble running the bases.

They did not field well.

Their pitching staff could not locate their pitches.

The club was repeatedly burned by its mistakes.

The Mets’ offense, and the Astros’ similarly wild pitching, helped them stick around, but manager Buck Showalter’s crew wound up narrowly making more mistakes than its opponents did.

The Astros were the less-worse club Wednesday in a 10-8 Mets loss at Minute Maid Park that finished off another disappointing series.

The Mets (34-40) lost for the 13th time in their past 17 and now have gone six straight series without a series victory.

Signs of progress for the talented team have repeatedly cropped up — Max Scherzer’s brilliance Monday was a nice sign — but a step back always has followed.

“We’re going to get out of it,” Daniel Vogelbach said after he drove in three runs Wednesday. “We’re going to go on a winning streak. I don’t know when that is; I wish I could tell you when. But I truly believe it is going to happen.”

The step forward Wednesday came on offense, as the Mets worked the Astros’ staff for eight walks, 10 hits and eight runs.

But in the past three and a half weeks, the Mets have scored at least seven runs in seven games, and they have lost six of those.

The retreating steps were everywhere else you looked on Wednesday:

• The Mets’ pitching staff, led by Tylor Megill, issued eight walks.

•  Pete Alonso ran outside the baselines, costing the Mets runs.

•  A catcher’s interference by Omar Narvaez and two wild pitches in the first inning led to a pair of runs.

• With the Mets down by a run in the seventh inning, Brandon Nimmo got thrown out at second trying to stretch a single into a double.

•  The Astros scored their last run, in the bottom of the seventh, when Adam Ottavino gloved a squeeze bunt and tried to flip the ball home, tossing it too high, however.

Narvaez had to leap for the throw, and by the time he came down, Corey Julks had scored.

The tone was set immediately, when Alonso tapped back to Cristian Javier with the bases loaded and none out in the first inning.

That began what looked to be a 1-2-3 double play, but Houston catcher Martin Maldonado’s throw to first went into right field.

A couple of Mets runs were wiped away, however, because Alonso ran on the grass and home-plate umpire Brian O’Nora ruled him out.

“We had some missed opportunities on both sides of the ball today,” said Alonso, who did not dispute the call. “For us, that was the difference-maker.”

There were smaller missed opportunities in a game the Mets nearly pulled out.

They escaped from holes of 2-0 and 6-4, but could not climb all the way back from a 9-6 deficit.

Alonso’s two-run home run in the sixth brought them within one at 9-8.

They had another chance in the inning, when Brett Baty smacked what would have been an RBI single, but Julks made a great diving grab in left.

An inning later, Nimmo led off with an opposite-field blast that missed being a home run by a couple feet.

It bounced off the wall, and Nimmo was thrown out trying to stretch the long single into a double.

“We don’t want to make any mistakes,” Showalter said after his club fell six games under .500. “Guys that are really good baserunners and good defenders are going through a period of where that’s not always the case.”

The biggest missed opportunities, though, came on the mound.

Megill followed up an excellent start against the Cardinals last week with a nosedive.

The inconsistent righty recorded eight outs and allowed eight total hits and walks.

“It’s more so the embarrassing part for me,” said Megill, who allowed five runs [four earned]. “Our offense is going out there and putting up great at-bats and getting the run support. … I’m not helping the team out because I’m not doing my job.”

Following Megill was Dominic Leone, who allowed four runs in 1 ¹/₃ innings.

The hole finally was too big. Will the same be said about the Mets’ 2023 season?

“Obviously not where we want to be,” Alonso said. “But we just need to keep playing hard.”