The Giants filled one of the two vacancies in their starting rotation this week by signing right-hander Adrian Houser to a two-year deal with a club option for 2028. With one spot addressed, how will San Francisco go about finding a fifth starter?

During a call with reporters on Friday morning after the signing became official, general manager Zack Minasian reinforced the Giants’ desire to add two starters this offseason and give their younger arms more time to develop. Still, Minasian added that the final spot in the rotation could be filled internally.

“I don’t know if I would characterize it quite as a need at this point, given the group of younger starters,” Minasian said when asked if the Giants needed one more starter. “I think there’s seven or eight players; if we can’t develop a couple of those, shame on us. I believe in our development system and our pitching group, but also, there’s something to be said for these pitchers being allowed to go through natural maturation.

“You look at Logan Webb combined in 2019 and 2020, and it was 20 starts of a plus-five ERA. Now, we have a true ace of the staff. So, you understand some pitchers have to go through that.”

The Giants aren’t lacking for internal options, a group that includes Hayden Birdsong, Carson Whisenhunt, Blade Tidwell, Trevor McDonald, Kai-Wei Teng and Carson Seymour. But those internal options don’t have an extended track record of success at the major- league level.

Birdsong, 24, pitched well for two-and-a-half months but was optioned to Triple-A Sacramento after suddenly losing his command and never returned. Whisenhunt, 25, struggled during his brief time in the majors. McDonald, 24, impressed down the stretch but has only thrown 18 innings in the majors. Tidwell, 24, only has two major-league starts.

The Giants likely won’t invest the nine figures needed to land marquee free agents Framber Valdez, Ranger Suárez or Tatsuya Imai, but there are still many starters available as the calendar year nears a close.

Zac Gallen, 30, is coming off the worst season of his career but is a former All-Star. Chris Bassitt turns 37 in February but has pitched at least 170 innings over the last four seasons. Max Scherzer, 41, played under new Giants manager Tony Vitello at the University of Missouri, and held his own in the postseason despite dealing with injuries during the regular season.

The Giants witnessed firsthand the volatility of young starting pitchers last season. It’s possible those arms take a step forward, but it’s also possible no one from that group emerges as a viable rotation option. For San Francisco, acquiring another proven starter would raise the rotation’s floor and give the likes of Birdsong, Whisenhunt and Tidwell more time to develop.

“We’ve talked since the beginning of the offseason that it would be ideal to add two starting pitchers and continue to give those younger arms more time,” Minasian said. “We’re going to need them one way or another, but I think getting Adrian in the fold at least gives you some comfort that we have legitimate fifth starter options. But you never stop looking. If we can find somebody that we like through free agency or trade, we’ll be active there.”

Houser, who will be 33 in February, wasn’t considered one of the top pitchers on the market but landed a multi-year deal after posting a 3.31 ERA over 21 starts with the White Sox and Rays. He’s had an up-and-down career — including an ERA of 4.76 from 2022-24 — but Minasian believes Houser’s velocity spike can lead to sustained success.

In 2024, Houser had an average fastball velocity of 92.8 mph. In ‘25, thanks to a small mechanical tweak with his hands, Houser upped his average fastball velocity to 94.6 mph.

“We really believed in the mechanical changes he made,” Minasian said. “He talked about getting more into his backside and freeing up his arm path. It led to a 2-mile-per-hour velocity increase. I think he commanded the ball better, he spun the ball better. He was able to maybe widen his mix of usable pitches.

“He’s a very athletic pitcher to begin with, and I think when things finally got synced up for him last year, that’s when we really saw him take off.”

Worth noting

The Giants designated outfielder Wade Meckler for assignment to make room on the 40-man roster for Houser. Meckler, 25, batted .232 with an OPS of .578 in 58 at-bats with San Francisco in 2023.
The Giants conducted a medical review prior to signing right-handed reliever Jason Foley, who underwent season-ending shoulder surgery last May. Foley will not be ready to pitch until midseason, and Minasian did not want to try to pinpoint a specific date that Foley could return. Outfielder Joey Wiemer was designated for assignment to make room for Foley on the 40-man roster.
Minasian said he’s excited to watch Logan Webb pitch for Team USA in the World Baseball Classic but added he’d be “lying if I said I wasn’t going to be holding my breath watching him pitch.” Webb will be monitored by head athletic trainer Dave Groeschner, who will also work for Team USA.
San Francisco has yet to finalize the specific roles for its new coaching staff. Minasian said Vitello is still looking at different alignments.
Minasian confirmed right-handed reliever Gregory Santos has signed a minor-league deal with the Giants with an invitation to spring training. Santos, 26, made his debut with San Francisco in 2021 and has a career 4.17 ERA and 3.48 FIP over parts of five major-league seasons.