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Trade Proposal: Fresh start for Isan Díaz

Review our four-player trade proposal involving the Nationals and Marlins.

Isan Diaz #1 of the Miami Marlins throws out a runner at second base against the Colorado Rockies at loanDepot park Photo by Michael Reaves/Getty Images

This will be the third installment of my 2021 midseason article series presenting the framework for Marlins trades that could hypothetically happen right now. Those last two words are key, because my ideas tend to age very quickly—it’s no longer realistic to expect the Fish to invest millions of dollars in a rental infielder or flip Garrett Cooper for younger talent (he’s on the injured list with a lumbar strain). But I swear, they made sense in the moment!

In October 2018, the Marlins sent reliever Kyle Barraclough to the Nationals for international bonus pool money. The next year, Miami selected right-hander Sterling Sharp from the Nats in the Rule 5 draft. Otherwise, these NL East rivals haven’t done any major transactions with each other since the Florida Marlins days.

Is the fit and timing finally right for a classic “change of scenery” deal?

The Washington Nationals trade INF Carter Kieboom to the Miami Marlins for INF Isan Díaz, LHP Richard Bleier and RHP Chris Mokma.


Former first-round MLB Draft pick Carter Kieboom was the consensus top prospect in the Nationals organization entering the 2019 and 2020 seasons. Kieboom ascended the MiLB rungs as a shortstop, but beginning at the Arizona Fall League, he was gradually moved off of that position. All the while, he played against significantly older competition and posted good-to-great offensive numbers (career .283/.379/.462 slash line in the minors).

Kieboom homered in his major league debut on April 26, 2019, then did it again two days later.

He has not gone deep in 43 Nats games since then. No barrels during that span, either (as defined by Baseball Savant). Kieboom rated as a solid fielder at third base during the 2020 campaign. Unfortunately, those contributions were canceled out and then some by his lack of pop. His .010 isolated power was the lowest in the majors (min. 100 PA).

So far this season, Kieboom had an oh-so-brief cup of coffee in The Show—pinch-hitting appearances on April 6 and April 7—but has otherwise been assigned to Triple-A. He enters Wednesday slashing .233/.395/.356 for the Rochester Red Wings with 3 HR and nearly as many walks (16.7 BB%) as strikeouts (20.2 K%), plus he has maintained a perfect fielding percentage through 26 games at the hot corner. It’s hard to deem that a success when he already played at this level two years earlier.

In Washington, replacement-level Starlin Castro continues to get everyday reps at third base while veteran Josh Harrison is having a solid campaign at second base. Their right-handedness doesn’t lend itself to timeshare opportunities for Kieboom (who’s also a righty). However, if the Nats felt the 23-year-old was a meaningful upgrade over Castro, wouldn’t they have pulled the trigger on that move by now?

There are no such roadblocks for Kieboom on the Marlins. Yes, Miguel Rojas is on the verge of returning from the injured list, but they’ll have a void at third base for the foreseeable future due to Brian Anderson’s left shoulder subluxation. Even before that setback, general manager Kim Ng had been non-committal about BA’s future in Miami.

Including 2021, Kieboom has two minor league options remaining. He’ll be under club control through at least the 2026 season.


Fish Stripes original GIF

Isan Díaz has plenty in common with Kieboom:

  • Great production at Triple-A in 2019
  • Blocked from a call-up by Starlin Castro
  • Home run in his MLB debut
  • Severe offensive struggles at the major league level since then

Marlins fans reading this don’t need a spiel on where we stand with Díaz—through parts of three seasons, he’s been one of the worst players in baseball.

Isan’s market value has rapidly depreciated, but he is far from a sunk cost. His major league 49 wRC+ and .265 xWOBA are in the same neighborhood as Kieboom’s (55 wRC+ and .277 xwOBA). Although the ship has pretty much sailed on him becoming a 50 grade, legitimate everyday-caliber player, his left-handedness complements a Nationals roster that still has aspirations to contend in 2021. And if the Nats somehow unleash his full potential, they’ll have the flexibility to keep him for the next half-decade.

The Marlins would need to include some sweeteners to balance this proposal.

Richard Bleier is still going strong at age 34. He’s got the lowest walk rate among all qualified MLB relievers this season. After an early-April case of gopheritis, he’s back to inducing tons of grounders. The trusty lefty (career 3.00 ERA) is owed less than a million dollars through season’s end and he can be retained for 2022 via arbitration.

A hefty signing bonus convinced Chris Mokma to turn pro after the Marlins selected him in the 12th round of the 2019 draft. Now 20, he’s among the youngest players in the Low-A Southeast league, starting once per week with mixed results (5.30 ERA, 1.40 WHIP, 17.4 K% in 35.2 IP).

This season for Jupiter, the 6-foot-4 right-hander is utilizing a true four-pitch mix (FB/CU/CH/SL). His fastball velocity sits in the low 90s and he shows good control for his experience level. An experimental rule change has led to huge increases in Low-A stolen base attempts and success rates, but Mokma has been great at controlling the running game regardless.

Baseball Trade Values considers this a fair deal. I think that BTV is too high for Díaz, but Bleier and Mokma are being underrated.

Baseball Trade Values
Baseball Trade Values

What do you think?


Marlins get Carter Kieboom. Nationals get Isan Díaz, Richard Bleier and Chris Mokmo. Fair deal?

This poll is closed

  • 29%
    Yes, fair deal!
    (53 votes)
  • 24%
    Marlins say no
    (44 votes)
  • 33%
    Nationals say no
    (60 votes)
  • 12%
    Both teams say no
    (23 votes)
180 votes total Vote Now