Jon Niese: dissed and possibly dismissed.

Pirates general manager Neal Huntington said he regrets acquiring Niese in exchange for second baseman Neil Walker this past offseason — and he’s reportedly shopping the former Mets left-hander before this year’s deadline.

“In hindsight, maybe the two fringe prospects and trying to figure out where to re-allocate the money might have been a better return [for Walker],” Huntington said Friday on 93.7 The Fan’s morning show. “That’s where the results take us.”

The Pirates’ starting rotation has been their Achilles heel, and Niese was demoted to the bullpen to begin the second half, according to the Pittsburgh Tribune. He called the first half the “worst of my career.”

The 29-year-old southpaw has posted a career-worst 5.13 ERA along with a 1.57 WHIP and .880 OPS against. He leads the National League in wild pitches with eight, and has given up 20 home runs, two shy of his career high.

“Given the thinness of the starting pitching market, given the dollars that we had available, we felt that that was our best return, and it has not played out that way,” Huntington said. “And that’s a challenge, we own that, we accept that.

“At the time Jon was one of the better starting pitchers available on the market given what we typically can do in this revenue stream, and that’s the reality.”

There’s a layer of irony here that may be delicious to Mets fans. Niese delivered a few passive-aggressive parting shots at the Mets, saying he was “relieved” to be leaving a crowded mix of starting pitchers in Queens and predicting he’d get a boost from joining the Pirates.

“I’m sure what I’ll appreciate more than anything is the way [the Pirates] play defense,” Niese said last December. “I’m looking forward to that.”

Nope. Opponents have a .322 average on balls in play against Niese. Meanwhile, Walker has performed well for his new team, batting .254 with 15 home runs, 37 RBIs and a .753 OPS while forming a dependable double play combination with Asdrubal Cabrera.