All of the Mets fans who howled about the Lastings Milledge trade last winter can pipe down now. Ryan Church is making the argument against sending the mercurial Milledge to Washington look silly — and making the Mets look smart in the process.

Church remains one of the young season’s most pleasant surprises for the Amazin’s, showing it yet again Friday night with a 2-for-4 showing that included a homer and three RBIs in their 7-2 win over the Diamondbacks.

That display kept Church’s average above .320 – he is the only regular in that territory — and helped the right fielder maintain his status as by far the Mets’ most consistent hitter this year.

Not bad for someone dismissed as nothing more than a part-time player by the lowly Nationals as recently as last summer.

“He’s been even better than I thought he would be,” Willie Randolph said of the 29-year-old Church. “He’s hit wherever we’ve put him, and his defense in right has been excellent. He’s been a nice addition.”

Church has been so productive that he prompted Randolph to move him into the No. 2 hole in the order in place of Luis Castillo.

That switch was billed as temporary at first and more of a concession to Castillo’s ailing knees, but Church appears to be making the second spot in the lineup look like his permanent home.

Having Church bat between leadoff hitter Jose Reyes and slugger David Wright certainly is doing wonders for the Mets’ win-loss record. Randolph’s club was 6-1 through Saturday with Church hitting second in the lineup.

“I feel really, really comfortable, especially when Jose is going and is getting on base,” Church said of batting No. 2. “It makes it easier for me to move him over or bring him home because I know I have Wright and the big boppers right behind me.”

Randolph, who remains loyal to Castillo and still calls him “one of the better No. 2 hitters in the game,” stubbornly insists that Church’s hold on the second spot isn’t concrete.

Despite Randolph’s allegiance to Castillo, the Mets appear to be much better served with Church hitting second because of Church’s lopsided power advantage.

The homer Church hit Friday already was his fourth this season, while Castillo has just four homers in the past three seasons combined.

“Just luck,” Church said with typical modesty when asked about an early power surge that had him owning a .510 slugging percentage through Friday.

As well as quieting the critics of the Milledge trade, Church also is dispelling what he considered an especially unfair knock against him –- a supposed inability to hit left-handed pitching.

A lefty himself, Church had his playing time in Washington reduced the past two seasons because of his struggles against lefties (.229 last season). But that hasn’t remotely been an issue this year with Church hitting a robust .342 against lefties.

Church also has been outstanding in the field, playing a flawless right field (he had no errors while starting 27 of the Mets’ first 28 games) and giving Randolph one less thing to worry about.

“Ryan’s been so good that you never want to take him out,” Randolph said. “He makes it hard to get my other outfielders playing time. Those are the kinds of problems you like to have.”

Lastings who?