What Ketel Marte is Really Worth to the Diamondbacks

Why a recent reported trade package may fall far from the mark needed to obtain Ketel Marte.

Sep 2, 2025; Phoenix, Arizona, USA; Arizona Diamondbacks second base Ketel Marte (4) celebrates his three run home run in the seventh inning of the game between Arizona Diamondbacks and Texas Rangers at Chase Field. Mandatory Credit: Arianna Grainey-Imagn Images | Arianna Grainey-Imagn Images

Arizona Diamondbacks All-Star Ketel Marte has been at the forefront of trade rumors this offseason. That is because the team made clear they would listen to offers for their superstar second baseman.

Their motivation for doing so is clear. They have numerous holes to fill on their roster, most notably but not limited to the pitching side of things. With a somewhat limited payroll budget they will not be able to fill those holes by free agency alone.

Furthermore, the vast majority of teams are not looking to take on prospects in deals for major league players at this time. That may leave the team with little choice but to trade their mercurial superstar to achieve their goals.

Mike Hazen explained this dilemma in an interview with the Arizona Republic's Nick Piecoro.

“It’s just a question for us of, how realistic is putting all those moves together in aggregate that may equal one of something else. Or maybe you don’t get all of it, but you put a big dent in it. That’s the challenge.”

Left unsaid by Hazen is the reality that Marte will achieve 10 and 5 rights 10 days into the MLB season. That means he will have full right of refusal to any trade. So that does reduce some of the Diamondbacks' leverage. It's now or never if the team wants to trade him unencumbered.

The question then becomes just what is Marte's trade value, and can the team realistically expect to improve their roster and improve their chances of contention in 2026 and beyond by trading him. As yet, the D-backs have not found an offer to their liking.

What is Ketel Marte's Market Value?

Marte has five years, $91 million left on his contract. It is backloaded, and there are significant deferrals, as $41 million of that amount is deferred to 10 years out from the year it is earned. That lessens the NPV (Net Present Value) by approximately $18.5 million.

MLB teams are paying approximately $11 million per WAR in free agency according to calculations run by Eno Sarris of the The Athletic. Taking that number, and Marte's projections, his excess value over his contract amounts works out to $81.5 million.

Ketel Marte Excess Value Over Contract | Jack Sommers

Ketel Marte Deferral Schedule | Jack Sommers

How Does Rumored Tampa Bay Trade Proposal Stack Up?

In the Piecoro article mentioned above, two starting pitchers from the Tampa Bay Rays, Ryan Pepiot and Shane Baz, were mentioned as players that had been discussed. Both pitchers are are roughly league average starters.

FIP-, xFIP-, and ERA- are park- and league-adjusted metrics from FanGraphs. League average is 100, lower is better than average, higher is worse. Below is how these two pitchers performed over the last two seasons relative to league average. Their 2026 Steamer projections for ERA and FIP are also included.

Shane Baz and Ryan Pepiot Statistics | Jack Sommers

The above indicates both these pitchers are approximately league average. The MLB average for starting pitcher ERA in 2025 was 4.21, and the projections in the table above are also roughly league average.

If healthy and pitching a full compliment of innings, they are both projected to produce about two WAR in 2026. Both are entering their first year of arbitration, and will be free agents in 2029. The below table indicates both have a value slightly in excess of $40 million for the life of their contracts.

Shane Baz and Ryan Pepiot Excess Value | Jack Sommers

At first glance the total of $82.3 million shown above would appear to match Marte's $81.5 million value. But there are several factors to consider that skews that appearance of equal value.

The first is the 2026 WAR projections. Marte alone is projected to outperform these two pitchers by himself, 4.5 to 4.0 WAR. That does not make the D-backs a stronger team on paper for 2026, a focus year of course.

The second is that such a deal is trading one roster spot for two. If the D-backs simply held on to Marte, and promoted Cristian Mena, for example, they come out even further ahead on paper. Mena is projected to produce 0.8 WAR in 73 innings in 2026, with a 4.38 ERA.

Mena was 20% better than league average in 2025 at Triple-A Reno, and flashed his readiness in 6.2 innings in MLB in 2025. He will be 23 years old in 2026.

Combining Marte's 4.5 with Mena's 0.8 WAR would give the team 5.3 WAR, widening the gap for 2026.

The final factors here are the reliability of the projections themselves. Marte's performance at a high level is well established. The projections above already take into account decline years as he reaches his middle thirties. While Marte has missed some games due to injury, he's also averaged 137 games and 596 PA over the past three seasons.

Pepiot and Baz are pitchers, and thus inherently prone to injury. Baz has already had Tommy John Surgery. Neither pitcher has exhibited a true breakout to be above-average players.

The Diamondbacks are not going to get back the best player in the deal if they trade Marte. If they trade him, they are looking to fill multiple holes. The Tampa Bay proposal is not enough to make up for all the factors listed above.

The D-backs must do better if they trade Ketel Marte. For more on this topic, be sure to check out the Snakes Territory Podcast where Jesse Friedman and I discussed this situation.