Thus far, the 2018-19 offseason has been most notable for how much is left unresolved at this somewhat late hour. Most notably, Bryce Harper and Manny Machado remain unsigned, as do the likes of Dallas Keuchel, Craig Kimbrel, and Marwin Gonzalez. Another lingering subplot is Miami Marlins catcher J.T. Realmuto and the persistent trade rumors regarding him. 

Realmuto, of course, has not yet been dealt, and the Marlins' mixed signals on the matter don't really give us any hints about when or whether the All-Star catcher will be moved. Because Realmuto toils for an organization that's become something of an afterthought, maybe you're not thinking of him as being one of the biggest names of the offseason. In case that describes you, we're here to lay out the essentials of L'Affaire Realmuto-Marlins. 

Realmuto is very good

He's a catcher who's going into his age-28 campaign and who boasts a career OPS+ of 111. Framed another way, Realmuto over the course of his career owns a slash line of .279/.327/.442 despite playing his home games in a ballpark that's a pretty tough environment for hitters. Over the span of his career, MLB catchers have batted .241/.308/.387. As you can see, Realmuto has been much better than the average catcher when it comes to production at the plate. 

As well, he's a solid defender. Over at Baseball Prospectus, the advanced catching metrics grade Realmuto as having been a major defensive asset in 2017 and a bit above average in 2018. He's not an elite defender at the position, but he looks like an asset. He's also proved himself capable of working more than 1,000 defensive innings in three of his four full seasons in the bigs. 

None of this is all that surprising. He's a former top-100 overall prospect who back in 2010 slipped to the third round only because of concerns about his swing mechanics and his commitment to Oklahoma State. 

He's coming off a stellar 2018 

Peep Realmuto's numbers from last season:

player headshot
J.T. Realmuto
PHI • C • #10
BA0.277
R74
HR21
RBI74
SB3
OPS.825
OPS+131
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That's elite production as catchers go, and for his troubles Realmuto made the All-Star team and won the Silver Slugger at his position. The 2018 season was his age-27 campaign, and that's an age at which players sometimes level up in terms of skill and outputs, and that may be the case with Realmuto. 

Realmuto's 2018 gains may be sustainable

Even if Realmuto regressed to pre-2018 levels, he'd still be an upgrade at the position for most teams. However, there's reason to think that the strides he made in 2018 may carry over. Last season, Realmuto increased his fly-ball percentage modestly while also making significant strides with his rate of hard-hit balls. 

Now we'll turn to an advanced metric called expected weighted on-base average (xwOBA). This metric grows out of wOBA, which assigns proper value to every possible offensive event that happens while a batter is at the plate. Those proper valuations of singles, doubles, homers, walks, etc., distinguish wOBA from more traditional measures like AVG, OBP, and SLG. Also, for simplicity wOBA is scaled to look like OBP, which means that, say, .400 is elite and .290 is pretty poor. For instance, Babe Ruth is the all-time leader with a patently absurd wOBA of .513.

All of that brings us back to xwOBA, which is an estimation of what a hitter's wOBA should be based on things like exit velocity off the bat and launch angle. XwOBA attempts to strip away luck -- bad or good -- and defensive play from wOBA and identify a hitter's baseline skill. It's useful for getting an idea of how a hitter figures to perform in the near-term future. Basically, if a hitter's xwOBA is significantly lower than his wOBA, he's probably going to come back to earth at some point.

As for Realmuto, last season he authored a wOBA of .353. Meantime, his xwOBA checked in at .350. That's a mostly insignificant margin, and that means his bust-out in 2018 was mostly reflective of skills growth as opposed to good fortune. This merit, of course, isn't lost on teams that are interested in Realmuto.

He's got two years of team control left

Realmuto isn't a walk-year fix. He enters the 2019 season with just over four years of major-league service time, which means he won't be eligible for free agency until after the 2020 season. So any team that trades for him will have Realmuto for his age-28 and age-29 campaigns, barring an extension. Realmuto will make $5.9 million for the upcoming season and receive a big bump for 2020 as a third-year arbitration-eligible player. Even so, he's almost certainly going to be a bargain at those rates. Teams of course are -- to the point of dull excess -- all about player control these days, and that adds greatly to Realmuto's appeal. Also implied, of course, is a two-year negotiating window or so during which the two sides could agree to a contract extension. 

The market for him is reportedly still heated

We've seen a number of teams address catcher needs already this offseason. The Mets, for instance, inked Wilson Ramos; the Nationals traded for Yan Gomes; the Brewers landed Yasmani Grandal; and Jonathan Lucroy (Angels), Brian McCann (Braves), and Russell Martin (Dodgers) also found new homes. That said, as the number of teams in need of catching help has dwindled, so too has the supply of available backstops. That, in turn, means there's still enough of a Realmuto market for the Marlins to hold out for what they truly want. 

Thursday, Frisaro reported that the Marlins' talks of a Realmuto trade were in "advanced stages."

Again, Realmuto's a rare talent given his ability to produce with the bat while capably manning a vital and grueling defensive position. It follows that lots of teams would be interested, even as we head toward February.

Some talks have gotten specific

Is the end game near? Specific names are beginning to leak out, which is sometimes a sign that discussions are advanced: 

Francisco Mejia, whom the Padres acquired from the Indians in exchange for Brad Hand and Adam Cimber, is one of the top catching prospects in baseball. Obviously, the Marlins would love to land a replacement for Realmuto, and Mejia certainly fits the bill. As for the Dodgers, catching prospect Keibert Ruiz has been a rumored Miami target, as well as outfield prospect Alex Verdugo and outfield Joc Pederson. 

Most recently, though, the Reds have been buzzing: 

The Marlins clearly want multiple prospects, and they'll no doubt that at least one of them be a frontline, top-50 sort. Given Realmuto's value and control, that's a reasonable ask. 

The Marlins don't really have a good reason to keep Realmuto

After a change in ownership, the Marlins parted ways with the likes of Giancarlo Stanton, Christian Yelich, Marcell Ozuna, and Dee Gordon. That directly abetted a 98-loss season in 2018. The rebuild has been questionably executed in terms of the prospects the Marlins received in those deals, which did not net a single consensus top-100 prospect. They're not going to be good anytime soon (the SportsLine Projection Model tabs them for 99 losses in the upcoming season), and by the time Miami does matter again Realmuto will almost certainly be playing for someone else. Best to trade him now while he has those two years of control and is coming off a career year. 

Given that contending teams generally don't like to trade for a new starting catcher during the season, don't be surprised if Realmuto gets moved before opening day. If that happens, then also don't be surprised if Realmuto winds being one of the most important players to change uniforms during the offseason of 2018-19.