Leaving This Top Prospect Unprotected Could Cost Astros in Rule 5 Draft

The Houston Astros had key decisions on several young players at the Rule 5 deadline. One pitcher is in danger of being selected.

Houston Astros hat and glove in the dugout during the second inning against the Kansas City Royals at Kauffman Stadium. | William Purnell-Imagn Images

The Houston Astros made the logical decision earlier this week when they moved top pitching prospect Miguel Ullola to the 40-man roster.

The right-hander, who is close to making his Major League debut, would have been left exposed to the Rule 5 draft otherwise. That draft is next month at the MLB winter meetings. But, the Astros left another player exposed that one publication, Baseball America (subscription required) believes could be selected — pitcher Alimber Santa.

Santa is another Top 30 prospect, per MLB Pipeline. Ullola, a starting pitcher, is ranked No. 5. Santa, a reliever, is ranked No. 13. Like Ullola, he ended last season at Triple-A Sugar Land on the doorstep of the Majors.

The Astros are taking a risk hoping that other teams will pass on him next month. It could cost Houston a future reliever.

Why Alimber Santa Could Be Drafted

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The 23-year-old Santa has been with the Astros for five seasons after he was signed out of the Dominican Republic. Due to that service time, he was Rule 5 eligible. Houston left him unprotected as he was coming off a career-best season as a reliever. He went 3-2 with a 2.31 ERA in 2025. He had six holds and two saves in four chances. He struck out 82 and walked 39 in 70 innings as batters hit .185 against him.

That’s the sort of profile that the Astros could use in their own bullpen, writes Baseball America’s staff, even as he struggled with a 27.9% walk rate. The staff wrote that he has a deep pitch mix that features several different pitch shapes with good spin.

“He shows a good blend of out-generating skills and the ability to induce both ground balls and whiffs,” wrote the publication.

The Astros had to deal with a numbers game on the 40-man roster, as they had a significant number of arbitration-eligible players that are integral to next year’s team. Houston tendered 11 of them contracts on Friday, signed two others and traded another. Even with all of those moves, they have a full roster. Protecting Santa would have meant releasing a veteran.

Now, Houston must rely on the Rule 5 process being prohibitive to another team taking Santa.

If a team selects Santa, he must be assigned directly to that team’s 26-man roster in 2026 and pay the Astros $100,000. If that team opts to remove him from the roster at some point, he must go through outright waivers and be offered back to Houston for $50,000 if he clears waivers. If a team takes Santa, it will have room on its 40-man roster and some belief that he can contribute in 2026.

If none of the 29 teams agree, the Astros dodge a bullet, save a veteran’s roster spot and can continue Santa’s development at Triple-A. But it’s a risk.