The Mets never learn. Just a few days after Mariano Rivera tore his ACL roving the outfield in batting practice, the Mets made it mandatory for their relief core to shag flies before every game.

Before Friday night’s game against Arizona, the entire bullpen was in the outfield during batting practice. Not only were they forced to stay out there while their teammates hit, they remained for an additional 20 minutes to shag fungos from hitting coach Dave Hudgens.

“This has nothing to do with Mariano Rivera,” manager Terry Collins said adamantly. “It’s a defensive drill. The fact that Batista, Acost and Francisco are the only ones out there right now is merely a funny coincidence.”

The Mets won’t outwardly say it, but it’s clear – they’re trying to injure their pitchers. Coming into play on the weekend, the Mets’ pen ranks 27th in baseball in era, giving up 46 earned runs, the most in the league.

“They’re definitely up to something,” said a prominent Mets beat reporter. “They’re not just hitting them fly balls, they’re making them run and dive for gappers. I saw Jon Rauch literally jump seven feet over the wall for one of David Wright’s BP balls … actually he may have just been standing there.”

While their methods may seem unorthodox, a few of the pen arms have injury related outs in their contracts, which could take the Mets off the hook for millions of dollars.

“Look, I’ll be honest, I don’t mind shagging balls,” said fireballer Bobby Parnell. “The way I’ve pitched these past few years, I may not have a future on the hill. Maybe I’m the next Rick Ankiel.”