San Francisco Giants May Be Set For Major Rotation Shakeup After Rookie’s Struggles

On Tuesday, August 19, 2025, the San Francisco Giants suffered a 5-1 loss at the hands of the San Diego Padres due in large part to a rough day from starting pitcher Kai-Wei Teng. 

Teng, 26, took the loss against the Padres after making it through only 3.1 innings with 3 hits and 3 runs allowed (2 earned). He walked a batter and hit two batters in his outing as well. 

Teng looked great in his first MLB win on August 8, 2025, throwing 5 innings and surrendering only 3 hits and no runs. But the rest of his MLB tenure thus far has been poor. He hasn’t made it out of the fourth inning in his other three outings. His ERA is ugly, at 8.78. 

After the Tuesday loss, Melvin did not commit to Teng making his next scheduled start, which would come against the Milwaukee Brewers on Sunday, August 24, 2025. That could mean the Giants will send Teng back to AAA in favor of giving another pitcher, No. 14 prospect Blade Tidwell, a shot. 

Melvin’s lack of commitment to Teng makes it clear the Giants will at least consider other options. 

The Giants’ Young Pitcher Problem

The Giants could have one of the best rotations in baseball if one of the young starting pitchers they have employed this year developed into a reliable rotation arm. 

Logan Webb, Robbie Ray and Landen Roupp have been great. Justin Verlander has been mediocre, but not as bad as people think, he’s just had horrific luck. 

But no one from the cast of Hayden Birdsong, Kyle Harrison, Carson Whisenhunt and Teng has developed into an MLB starter that San Francisco trusts, even in the No. 5 spot. 

Harrison was probably the best of those four, but he dealt away to the Boston Red Sox in the Rafael Devers trade. 

Whisenhunt’s first MLB tenure wasn’t entirely a disaster. He made three starts and pitched to a 5.02 ERA. Like Teng, he picked up his first MLB win after one good start where he went 5.1 innings and allowed only 1 earned run. He also proved to eat innings decently even during bad starts. 

But Whisenhunt’s demotion only makes Teng’s potential demotion even more likely. By every metric, Whisenhunt was a better pitcher than Teng, and the Giants gave him less chances to prove it. 

If Teng is held to the same standard, Blade Tidwell is a great candidate to make the Sunday start. 

Erik Miller Injury Worse Than Initially Feared 

The Giants got some more unfortunate pitching news on Tuesday August 19, 2025 when lefty relief pitcher Erik Miller reaggravated his elbow injury. The Giants have to shut him down from throwing for two weeks as a result. 

Miller, 27, was having a superb season out of the bullpen with a 1.50 ERA in 36 games. Now, he may not return until 2026. 

Miller’s absence has been an underrated reason why the Giants bullpen has struggled in the second half of 2025. Once the strength of the team, the bullpen has given up several late inning leads in recent weeks. 

Giants insider Andrew Baggarly views Randy Rodriguez and Ryan Walker as the only Giants pitchers that are locks to be in the 2026 bullpen. 

Both the bullpen and the rotation will be difficult problems to solve internally because the Giants do not have top pitching prospect talent. They need underrated, overlooked pitching prospects to step up and prove themselves. 

Giants fans, do you think Blade Tidwell should make a start over Kai-Wei Teng? 

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