PORT ST. LUCIE, Fla. -- Playing last summer for the Dodgers' Triple-A Oklahoma City affiliate, Jacob Rhame saw firsthand one of baseball's newer pitching trends play out before him. As Rhame logged his time at Triple-A, he watched the Dodgers option successful pitchers such as Josh Fields and Thomas Stripling to the Minors to make room for rested arms at the Major League level.

"You can be throwing your butt off, throwing well, but if you throw three days in a row they need a fresh arm," Rhame said. "It's just part of the game. You've got to know your role."

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As that trend grew popular in Oklahoma City, Scranton, Pa., and various other Minor League outposts around the country, the Mets took notice. Out of contention by early summer, New York began scouting other teams' relievers, looking for pitchers such as Rhame who featured elite strikeout rates, opponent exit velocities and spin rates.

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They used Trackman data at Port St. Lucie's First Data Field to identify Drew Smith , whom they eventually acquired for Lucas Duda . They saw wipeout potential in the 101-mph fastball of Gerson Bautista , who arrived with Jamie Callahan and Stephen Nogosek in a deal for Addison Reed . They imported live arms in Rhame (for Curtis Granderson ) and Ryder Ryan (for Jay Bruce ), each of them with histories of striking out more than 10 batters per nine innings in the Minors.

Four of the six now rank among MLB Pipeline's Top 30 Mets prospects. Rhame, Callahan, Bautista and Smith are all in big league camp.

"Everyone here has got an awesome arm," Rhame said. "We've all got talent. It's a big competition, really."

Almost as important, all of the relievers the Mets acquired have unused Minor League options, giving the Mets the exact sort of flexibility they crave.

It may seem like a small thing, but with relief pitchers contributing a higher percentage of innings than ever before in baseball history, it's critical. No longer can teams survive with seven-man bullpens. To the contrary, many clubs have already transitioned to eight-man 'pens, like the Mets did for much of last season. But even that is often no longer enough.

Beyond the extra arm, teams value optionable relievers who can shuttle back and forth from Triple-A at any time, with no penalty -- no risk of losing them to a waiver claim -- beyond a 10-day cooling off period following a demotion. That allows clubs to bring in fresh arms after using their bullpens heavily in an extra-inning game or on a night in which the starter did not go deep.

Logistically, it's a strategy that's easier for teams such as the Yankees that play within driving distance of their Triple-A club. But it is one the Mets nonetheless plan on embracing for a year with their Las Vegas affiliate, before shifting to Syracuse, N.Y., in 2019.

"To have a couple of optionable relievers, or one spot that you can do that with, is huge," manager Mickey Callaway said. "You have a 15-inning game, they're gonna go down. That's just how it is. We're going to bring them all in, those guys with options, and explain that to them, and they have to be able to handle that information, go down, get their work in in Triple-A so they can come back and help us.

"Those guys are going to matter in the long run. They will probably end up pitching in some pretty important games at some point. So they're very crucial for what we're trying to do."

The Mets will begin this season with a bullpen featuring at least three pitchers with accessible options, giving them such flexibility in spades. And while Rhame, Callahan, Smith and Bautista are unlikely to call Flushing home on Opening Day, it may not make much of a difference over 162 games.

"Obviously everybody wants to have the goal of making the team out of Spring Training," Smith said. "Everybody in here wants that. But if not, you still have a chance to be here. It's a long season."