Edwin Díaz is the Mariners’ MVP. Don’t trade him, you dummies.

Source: Baseball-Reference

Francisco Rodríguez, Bobby Thigpen, Éric Gagné, and John Smoltz. Those are the only names ahead of Edwin Díaz on the all-time single-season saves leaderboard. Currently Edwin sits sandwiched between two Hall-of-Famers in Smoltz and Trevor Hoffman; he needs just two more saves before the end of the season to take over third place all by himself. He is also the youngest player in the top twenty—no other player in MLB history has gotten to 50 saves younger than age 25, the age Craig Kimbrel was when he recorded 50 saves in 2013. This is rarified air, to be sure, almost as rare as it is for a reliever to be third in WAR on a team that includes Nelson Cruz and Robinson Canó. It’s difficult to overstate how special Edwin Díaz is, except to look at the company he keeps: Hall-of-Fame caliber players at the tender age of 24.

The list of 24-year-old relievers who have posted at least 2.0 fWAR in the last 30 years is just as impressive. It includes names like Chapman, Kimbrel, and Jansen—and also Rocker and Ayala. There have been 10 relievers who have crossed that two-win threshold since 1989. Díaz easily tops this list, but the seasons Aroldis Chapman and Kimbrel put up at the same age are extremely good too. To get a general sense of how elite, young relievers hold up over the next few years of their career, let’s see how these ten pitchers fared over the next four years.

Obviously, Chapman, Kimbrel, and Jansen are the biggest successes on this list. In their age-25 through -28 seasons, they averaged 2.2 fWAR per year. But even mirroring the careers of Francisco Rodríguez, Ugueth Urbina, or Ken Giles wouldn’t be a terrible outcome for the Mariners young closer. John Rocker and Bobby Ayala represent the worst-case scenarios, though neither really fits as a comparison to Díaz.

One of the main arguments for trading Díaz is a familiar one: “relievers are the most volatile commodity in baseball.” Trading Díaz right now would definitely be selling high, banking on the idea that he would blow up on someone else’s team, making that better than holding on to him too long. But when we’re talking about an elite level of performance like we’ve seen from Edwin this year, that success usually continues for years. Díaz might not reach the lofty heights we’ve seen from him this year, but it’s not unreasonable to think he’d produce five to eight wins over the next four years. If the Mariners have the next Chapman or Kimbrel or Jansen on their hands, that’s the kind of piece you build around. Yes, Chapman and Kimbrel were eventually traded away by their original teams, but only when they had a year or less of team control left.

And then there’s the additional value Díaz has to the Mariners right now. The roster, as flawed as it is, is built to win now. The way the payroll is structured combined with the age of the roster means there is no major teardown on the horizon. Díaz is the most valuable piece the Mariners could trade away this offseason to attempt to restock their barren farm system. But that feels like robbing Peter to pay Paul. He’s is the one asset that allows this roster to outperform their talent level. The Mariners’ current record is the only evidence needed to believe that. So if the Mariners have forced themselves into attempting to contend with what they’ve got for the next few years, Díaz is an absolutely necessary piece of that puzzle.

Relievers are becoming more and more valuable as the game pivots toward high-strikeout short-outings as seen with the “Opener,” and the revitalized “Fireman.” Almost every single team in playoff position in the American League added to their bullpen to give them an edge over their competition this season. We’ve seen the rise of the super-bullpen in places like Cleveland, Houston, and Oakland. The Mariners attempted to build something similar when they acquired Álex Colomé in May, who was himself a replacement for the injured/ineffective tandem of David Phelps and Juan Nicasio, but the rest of the bullpen has let them down. Moving Edwin Díaz would further weaken a bullpen that the Mariners will need at full strength if they’re hoping to sneak into the second Wild Card spot in the next few years.

With the high valuation of relief pitching, a trade package for the young, controllable Diaz would be tantalizing, as laid out by our respected but ultimately incorrect colleagues. But exactly what makes Edwin so special is also what makes it hard to pin down a trade market for him. As valuable as relievers are in the current market, especially if the Mariners tank next year and choose to deal Diaz at the trade deadline, when bullpen help is at a premium, they aren’t guaranteed a similar return. Diaz is a known quantity, and controllable for the foreseeable future; trading him for a “can’t miss” prospect sounds like a great idea until said can’t-miss prospect, well, misses. Sometimes you trade a half-season of Aroldis Chapman and get Gleyber Torres, an immediate Rookie of the Year candidate; sometimes you trade Chris Sale and get Yoan Moncada, still struggling to put it together at the big-league level a year and a half in: an everyday player, but not (yet, at least) the superstar the White Sox dreamed on when they sent away their scissor-happy ace. Or perhaps you acquire one strong year of Wil Myers followed by two years of meh production. Or Tim Beckham, traded for RHP Tobias Myers, who is following up a 3.4 fWAR season with a -0.6 one.

Or Jesus Montero. Sometimes you get Jesus Montero.

Even if the Mariners were guaranteed a top prospect or two, would that be enough to cover the value Díaz would return as a Mariner? Chapman, Kimbrel, and Andrew Miller were all traded when their team control had been reduced to a year or less. Each of them returned multiple top prospects. Díaz has four more years of team control and you’d expect a corresponding increase in value to cover that coveted team control. But then we’re talking a return that includes maybe three or four top prospects or established MLB talent. We think you’d be hard pressed to find an organization who would be motivated to move that much talent, even for a transcendent closer like Díaz.

Every outing, Edwin Díaz shows us a little more of who he is: a fierce competitor who wants to be the “bad guy” on the mound; a student of the game who constantly works to improve; a good teammate who celebrates when his peers make a great play just as much as he does striking out the side; a playful kid at heart who makes bets with his manager and wants to keep every ball from each of his fifty-plus saves. We have been privileged to witness some incredible players in Seattle sports over recent years, the elite of the elite in their respective sports: Sue Bird, Earl Thomas, Clint Dempsey. We are witnessing the rise of another in Edwin Díaz, homegrown superstar and potential Hall-of-Famer, our very own generational talent.

Do not trade him, you dummies.