After agreeing to a contract with free agent center fielder Harrison Bader on Monday, the San Francisco Giants had work to do trimming their roster. They would need to trade or waive a player to accommodate Bader on the 40-man roster, and on Thursday they found the solution. As first reported by Chandler Rome of The Athletic, the Giants agreed to send right-handed pitcher Kai-Wei Teng to the Houston Astros in exchange for catching prospect Jancel Villarroel. The Giants have since announced the move, and added that they also received international slot money in the deal.
Villarroel is an intriguing prospect who signed with the Astros out of Venezuela after the 2022 Dominican Summer League season. The right-handed hitter, who turned 21 a few weeks ago, spent the bulk of the year with Houston’s Low-A affiliate, where he hit .258/.360/.385 for a .746 OPS and a 123 wRC+. He played a few weeks with the Astros’ High-A affiliate to end the year, and figures to open the upcoming season with High-A Eugene. He has a decent amount of raw power — though that hasn’t really shown itself yet on the stat sheet — and decent bat-to-ball skills. He had just a 17.2% strikeout rate in Low-A last year. In the midseason 2025 rankings, Villarroel ranked as the Astros No. 13 prospect according to MLB Pipeline, and their No. 20 prospect according to Fangraphs. Earlier this month, Baseball America ranked the catcher as the No. 19 prospect in Houston’s system.
He’s a little bit of a project defensively at catcher, but also has experience all over the diamond. In his brief Minor League tenure, he’s seen time at every position except shortstop and pitcher.
As for Teng, it’s the end of a long, up-and-down tenure. And as the leader of the Kai-Wei Teng Believers Club, I’m pretty bummed seeing him leave. The righty came to the Giants in 2019, during his first full season of affiliated ball, in the Sam Dyson trade. He rose through the system as one of the organization’s top strikeout arms, but often struggled to control his walks and keep his ERA down.
The Giants rostered him as a Rule 5 protection prior to the 2024 season, but everything fell apart for him that year. He stopped striking people out, sported an awful 8.60 ERA in AAA, was even worse in his brief Major League stint, and was designated for assignment.
He re-signed with the Giants last offseason, and started to turn his career around. He was excellent for AAA last year, splitting time between the bullpen and rotation, where he had a 3.63 ERA and a 2.95 FIP, while his 14.05 strikeouts per nine innings were among the best in the Minor Leagues. That earned him another MLB opportunity, and the results in eight games were hot-and-cold: on the bad side, he had a 6.37 ERA and issued 5.16 walks per nine. On the good side, he had a 3.81 FIP, a 4.00 xERA, and 11.83 strikeouts per nine.
With the Giants entering the year with a full rotation, Teng was scheduled to join a very large group of unproven arms who would battle for a spot in the rotation and/or the sixth and seventh starter roles. That group includes fellow 40-man arms Hayden Birdsong, Carson Whisenhunt, Carson Seymour, Trevor McDonald, Blade Tidwell, and Keaton Winn. Given his strikeout ability, I thought Teng might have the inside position for a bullpen role, but either the Giants disagreed, or the Astros saw things similarly. It’s always hard to gauge with trades like this whether Teng was the outgoing piece because he was the player the Giants were ready to move on from, or he was the player that Houston was targeting.
Either way, the recently-turned 27-year old is headed back to the American League, and will get a chance to solidify his role in the Majors with the Astros. I, for one, will be rooting for him.
