The buzz that the Mets could trade for Marlins catcher J.T. Realmuto has picked up steam over the last couple of days. But even if they can, should they?
On the one hand, Realmuto couldn't be a more perfect fit. The major catch, though, is that they'd likely have to give up one of their core young Major Leaguers to headline the package: Michael Conforto, Brandon Nimmo or Amed Rosario.
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But if anyone's worth it, it might be Realmuto -- especially if the centerpiece is one of New York's outfielders, Conforto or Nimmo. One big reason: The difference between Realmuto and other catchers is much greater than the difference between Conforto or Nimmo and other outfielders. The other: Realmuto is a true star at a position where the Mets desperately need an upgrade.
Here's a two-part case for the Mets to jump on a Realmuto trade if the opportunity presents itself.
1. Realmuto is a huge competitive advantage
By overall value, Realmuto, Nimmo and Conforto have graded similarly. Realmuto was worth 4.8 Wins Above Replacement in 2018, per FanGraphs. That's about the same as Nimmo's 4.5 WAR in his breakout season; both marks are All-Star level. Over the last two seasons, Realmuto has accumulated 8.6 WAR; Conforto is not far behind, with 7.4 WAR from 2017-18.
But the difference is their position. Realmuto is extremely valuable because he's a catcher. As MLB.com's Mike Petriello noted earlier in the offseason, the catcher position has become extremely weak. Realmuto excels in every aspect of the game. 
Realmuto was a top-tier catcher in 2018, and more importantly, the 27-year-old has performed consistently at that level over the last several seasons.

Highest WAR among catchers, 2018
1. J.T. Realmuto, 4.8
2. Yasmani Grandal, 3.6
3. Francisco Cervelli, 3.3
4. Willson Contreras, 2.6
5. Wilson Ramos, 2.4
Highest WAR among catchers, 2016-18
1. J.T. Realmuto, 12.3
2. Buster Posey, 10.0
3. Yasmani Grandal, 9.0
4. Gary Sanchez, 8.9
5. Willson Contreras, 8.1
Even the leaderboards alone don't fully capture just how much Realmuto has stood out from the pack. Consider this: In both 2016, and overall from 2016-18, Realmuto's WAR has been three full standard deviations above the average for regular catchers (those with at least 250 plate appearances in '18, and at least 500 from 2016-18). In a normal data set, 99.7 percent of the values will fall within three standard deviations of the average. Realmuto has exceeded that. In other words, he has been an extreme outlier at the catcher position.
Nimmo and Conforto are young (both 25), and good. They're the type of players a team should want to retain. They're also controllable for longer than Realmuto -- Realmuto is under team control for two more seasons, Conforto for three and Nimmo for four. But Conforto and Nimmo just don't stand out from their outfield peers in the same way that Realmuto does from his. He's the type of player worth giving up a lot to acquire, even considering the years of control. (Shortstop, on the other hand, is a premium position where young talent is hard to come by, so it might be harder to part with Rosario -- who's just 23 and controllable for the next five seasons -- in that respect.)

2. Realmuto is a five-tool catcher
And he's really the only five-tool catcher. Realmuto hits. He has power. He's not only the fastest catcher, he's faster than the average Major Leaguer. He has one of the strongest arms in the game behind the plate, and plays above-average defense.
Statcast™ is great for capturing Realmuto's across-the-board talent. Here's how he checks the box for each of the five tools:
Hitting: Realmuto's expected wOBA -- a Statcast™ metric for overall offensive performance, based on quality of contact -- was .346 in 2018. MLB average xwOBA was .311. Realmuto's hard-hit rate was 40.8 percent (that's how many of his batted balls had an exit velocity of 95 mph or higher). MLB average was 35.4 percent.
Power: Statcast™ groups batted balls into different levels of contact, and the best is a barrel -- an ideal combination of exit velocity and launch angle, likely to be a home run or an extra-base hit. Realmuto barreled 9.0 percent of his batted balls in 2018, well above the MLB average of 6.7 percent. He hit 31 barrels overall, tied for second-most among catchers behind Grandal (35).

Run: Realmuto's average sprint speed in 2018 was 28.6 feet per second. That makes him MLB's fastest catcher. It also makes him fast, period. The Major League average sprint speed is just 27 ft./sec.
Arm and Defense: Realmuto's average arm strength on max-effort throws this season was 87.8 mph -- the second-hardest among regular catchers. His average pop time to second base on steal attempts was 1.90 seconds, the fastest in the game. For pitch framing, Realmuto got a called strike on 49.2 percent of borderline pitches, above the league average for catchers, 48.0 percent.
Compare Realmuto to the Mets' catchers of recent seasons, and it's night and day. It's been a major struggle for the Mets to find a reliable backstop. That goes for both offense and defense. At the plate, Travis d'Arnaud and Devin Mesoraco provided some power at times, but not a whole lot else. Defense is an even more glaring concern, especially the run game, which the Mets have been notoriously unable to control. Realmuto solves every problem.

There are some good free-agent catchers available this offseason -- Grandal and Ramos chief among them. But even Grandal isn't as complete a player as Realmuto, and Ramos' specialty is offense, not defense. Would keeping Conforto and Nimmo and signing Grandal be better than keeping one of the two, trading for Realmuto and, for example, signing an outfielder like A.J. Pollock?
It's not that Nimmo or Conforto would be easy to replace in the outfield. They wouldn't. But there are more good outfielders out there than there are good catchers, and finding a good catcher is of paramount importance in Flushing. Realmuto is exactly what the Mets need.