Nolan Arenado Traded to Diamondbacks: Fantasy Baseball Breakdown

A couple of bigger MLB trades went down on Wednesday. We'll go over the first one here, looking into the deal that sent Nolan Arenado to the Diamondbacks.

St. Louis only got pitching prospect Jack Martinez back. The Cardinals also sent $31 million to the Diamondbacks to help cover the $42 million remaining over the next two years. Arenado also had to waive his no-trade clause to help the deal go through.

Let's break down the real world and fantasy baseball implications of the deal.

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Arenado's Stats

Arenado took a big step back in 2025, so the D-Backs are hoping he bounces back in 2026.

Over 107 games, Arenado had a .237 average and .289 on-base percentage. He owns a career .282 average and .338 OBP over 13 seasons.

Last year, Arenado had 95 total hits over 436 plate appearances. He had 12 home runs, 18 doubles and a triple among his hits, along with 52 RBIs, 48 runs scored, three stolen bases, 28 walks and 49 strikeouts.

Over his career, he has flashed plenty of power, while sporting a good average and OBP. He doesn't steal many bases, but he also doesn't strike out a ton, so he ends up being a very good fantasy player.

Now the big question is whether or not he has any gas left in the tank. At 34 years old, he's past his prime and on the back nine of his career, but I believe he can still deliver decent results.

Outlook for Arenado and the D-Backs

Arenado should start daily at third base for the Diamondbacks, and probably hit in the bottom half of the lineup, if Arizona is at full strength.

With guys like Geraldo Perdomo, Ketel Marte, Corbin Carroll, Gabriel Moreno and others hitting ahead or around him, Arenado should have plenty of chances to drive in runs. The bottom of the team's lineup lacks true difference makers at this point, so him scoring a bunch of runs isn't super likely.

The first big thing for Arenado will be health. Last year was only the second time in a full season (so not 2020) that Arenado has failed to reach 130 games played, so I'm not too worried about that.

If he can stay on the field, then we will next have to see if he can bounce back as a hitter. I think he's too talented to drop off as hard as he did a season ago. A change of scenery could do him well, and he could be a sneaky-good fantasy asset.

Arenado won't be a high-end draft asset, but he still should be drafted in almost every league setup, and could become a daily starter if he turns things around.

Arizona had a need at third base, so Arenado joining the mix isn't a massive hit to any one player. There's a lot of projected platoons in the Arizona lineup, so most guys on the active roster are set up to be decent fantasy options, especially the ones that hit after Arenado.

Arizona does have some decent infield prospects, but apparently the team does not think any of them are ready to contribute to the big league team. Guys like Gino Groover, Demetrio Crisantes and Jordan Lawlar might have a harder time reaching the big leagues, unless there's injuries over the next couple years.

Arenado is a good veteran to learn from, so those younger players could also benefit in the long run from Arenado. For now though, the infield looks locked in with Marte, Arenado and Perdomo.

This move definitely gives the D-Backs a better chance to compete in 2026. It doesn't move the needle a ton, but if Arenado bounces back, then Arizona could make some noise in the National League.

Martinez's Outlook

Martinez is a 22-year-old right-handed pitcher who was drafted in the eighth round of the 2025 MLB Draft.

The 6-foot-4, 215-pound pitcher did not pitch professionally after his collegiate season ended last spring.

So the Cardinals are definitely taking a gamble on Martinez, who is years away from possibly contributing to a big league roster. At an advanced age for a prospect, he could move quickly through the minor league ranks, so he's a player to keep tabs on.

This trade was more of a way to rid the roster of a high-priced veteran in Arenado, because the return isn't anything special. Paying out some of Arenado's contract solidifies that take.

Don't sleep on Martinez though. In time, St. Louis could develop him into a worthwhile fantasy asset for you to take advantage of. There's clearly something they like with him, so at least keep tabs on him.

Outlook for the Cardinals

With Arenado out of town, third base will likely belong to Nolan Gorman. The Cardinals have been selling off MLB assets all offseason, and Brendan Donovan could be next.

Donovan is arguably the best hitter left in St. Louis, and his fantasy stock, along with most of his teammates, has fallen with all the moves the team has made this offseason.

Ivan Herrera, Alec Burleson, Lars Nootbaar, Masyn Winn and Jordan Walker also look like likely starters for the Cardinals. The bottom of the order and bench for the Cardinals is weak, so there's opportunity for others to play and make a difference.

J.J. Wetherholt is the team's top prospect and is expected to debut in 2026. Trading Arenado gives Wetherholt a chance to make the team out of spring training, and definitely at some point in 2026 (as long as he's healthy).

Three of the team's other top-10 prospects are catchers, so it will be interesting to see how the Cardinals get those guys to the big leagues and playing time.

There's several other prospects ranked in the top 30 who are expected to debut in 2026, but not many are infielders. Blaze Jordan is a corner infielder to keep an eye on.

Overall though, St. Louis' hitters have taken a hit this offseason after the team traded away Willson Contreras and now Arenado. If Donovan and others are shipped out, things could get even tougher.

The trade means the Cardinals are likely to be one of the weaker teams in the NL in 2026, but that opens opportunities for new players/prospects to help out.

We'll assess the Cardinals (and all MLB teams) in previews as the season draws closer, so check back for those articles, and fantasy baseball coverage all season long!