The top executive for the Marlins, Derek Jeter, must be getting a lot of phone calls lately. The Marlins have been trading stars and shedding payroll since early December. They traded Giancarlo Stanton and his enormous contract to the Yankees, while they offloaded outfielder Marcell Ozuna to the Cardinals. They have a couple stars left though, and both of them would likely welcome a trade to calling suitors. Catcher JT Realmuto reportedly requested a trade last week, and outfielder Christian Yelich is apparently “unhappy” with the direction the Marlins are going. There appears to be a match of needs and wants here between the Marlins and Rockies.

The Rockies could stand to have a better catcher. Despite the upcoming reunion with Chris Iannetta, catcher is probably still the Rockies’ weakest position, both in the short and long run. Going into 2017, it seemed Tom Murphy and Tony Wolters could make a solid platoon. Going into 2018, it seems they are better fits for backup roles at the MLB level. Right now, FanGraphs projects the Rockies to get 1.7 WAR from their catchers, which would be 27th in the majors.

Contrast that with the Marlins’ Realmuto. Coming off back-to-back 3.5-WAR seasons, he projects for about 3 WAR next year. That’s pretty good! Also good is that he has three more seasons before he becomes a free agent. For a catcher who is second only to Buster Posey in fWAR since 2015, that’s a really valuable player!

In the outfield corners, the Rockies have some young talent (see David Dahl and Raimel Tapia) and some veteran clout (see Ian Desmond and Gerardo Parra). However, all four come with some major concerns. Dahl missed the entire 2017 MLB season due to nonexistence back problems. Raimel Tapia, who destroyed the minors in 2017, didn’t do very well in his limited MLB time, especially on defense in the corners. Ian Desmond had the worst season of his career, posting some very concerning batted-ball stats. Gerardo Parra had a bounceback from having the worst season in the NL in 2016, but he doesn’t profile as an everyday player, fitting much better as a 4th OF. Together, FanGraphs projects them for a little less than 2 WAR total.

Over in Miami, Yelich has posted 4.5 WAR in each of the last two seasons, and in three of the last four. Still just 26, he’s under contract through 2022, on an extremely team-friendly deal that pays him just $58 million over the next five seasons (assuming the $15 million team option for 2022 is picked up). He looks set up to post another stretch of seasons around 4 WAR, and has long been seen as a player due to breakout as a legitimate superstar.

It would make a ton of sense for the Rockies to call the Marlins about their two young studs. But then there’s that prickly question when our conversation starts drifting to such areas: what would the Rockies have to give up to get them?

My favorite approach for answering this question is to consider the surplus value of the players at hand. Surplus value is defined as the difference between what salary a player would get as a free agent, and what they actually are making in their contract—i.e., a single season of 3 WAR is roughly “worth” $24-30 million on the open market, and if that player is making just $5 million, he has surplus value of ~$19-25 million. In theory, surplus value is a decent barometer of how valuable a player is in a trade. It’s important to note that surplus value is a blunt blade: it’s unwise to lean on it exclusively or to use it to cut too finely. That said, it can still help us figure out the broad-strokes of a “fair” trade.

J.T. Realmuto Surplus Value Year Age Proj. WAR Value Actual Surplus Year Age Proj. WAR Value Actual Surplus 2018 27 2.8 $23.8 M $4.2 M* $19.6 M 2019 28 2.8 $25.0 M $6.5 M** $18.5 M 2020 29 2.8 $26.2 M $8.5 M** $17.7 M Total - 8.4 $75.0 M $19.2 M $55.8 M

Christian Yelich Surplus Value Year Age Proj. WAR Value Actual Surplus Year Age Proj. WAR Value Actual Surplus 2018 26 4.0 $34.0 M $7.0 M $27.0 M 2019 27 4.3 $37.9 M $9.8 M $28.1 M 2020 28 4.3 $39.8 M $12.5 M $27.3 M 2021 29 4.3 $41.8 M $14.0 M $27.8 M 2022* 30 4.3 $43.9 M $15.0 M $28.9 M Total - 21.2 $197.4 M $58.3 M $139.1 M

The math, while inexact, shows why the Marlins are asking for a lot in return. Realmuto and Yelich are premium assets, each probably more valuable (in a trade) than Giancarlo Stanton or Marcell Ozuna, who the Marlins have already traded. While I can’t speculate on precisely what Miami’s demands are, we can look at the surplus value of prospects within the Rockies’ farm system, trying to make the numbers match.

Over at FanGraphs, they have licensed the prospect valuation model developed by Matt Swartz and The Point of Pittsburgh. This model is based on past scouting grades and WAR values and allows us to give a ballpark estimate to the trade value of a prospect. Here is the core chart:

The left column is for the “Future Value” grade on the 20-80 system, a scout’s estimation of a prospect’s overall potential. The other two columns give what history shows such a prospect has been “worth” in surplus value, depending on being a hitter or a pitcher. It’s important to note that these numbers are rough, rough estimates, even before considering the uncertainty in a scout’s judgement. On average, though, this chart is a reasonable guide to valuing prospects in trades.

The elephant in the room, as far as Rockies prospects go, is Brendan Rodgers. He’s the team’s clear best prospect, a former no. 3 overall pick, and figures to debut in the majors later this year. Would the Rockies consider dangling him in a trade? I strongly doubt it, but I also strongly think they should consider it under the right circumstances. Rodgers is viewed as a ~65 FV prospect by most reports, putting his likely surplus value somewhere in the neighborhood of $60 million to $80 million.

I personally wouldn’t want to trade him for just J.T. Realmuto; I’d strongly prefer a deal built around several lesser prospects (and perhaps including Tom Murphy or Tony Wolters). However, if the Rockies want Yelich, it’s really, really hard to imagine the Marlins would part with him without getting Rodgers and more in return. If the Rockies were to shoot for the moon and try to get both, I would consider it impossible for the Rockies to keep Rodgers.

I understand the extreme hesitancy to move him: he has All-Star potential in the middle infield, where the Rockies will have a hole with the likely departure of D.J. LeMahieu after this season. On the other hand, Realmuto and Yelich are a 7-WAR combo now (with potential for more), paired up for three more seasons (and two on top with Yelich alone). The Hail-Mary trade would gut the top of the Rockies’ farm system, but it would also make them (in my mind) wild-card favorites in the NL, and a challenger to the Dodgers if things break right. With Blackmon and Arenado looking at free agency soon, going all-in on this window right now might be the best option.

If I’m Jeff Bridich, I’m calling Jeter, and when he asks about Rodgers, I’m not hanging up.