Giants select Seth Lonsway, giving left-hander his MLB debut opportunity

The Giants selected the contract of left-hander Seth Lonsway from Triple-A Sacramento ahead of a Saturday doubleheader with the Diamondbacks, the club announced. Lonsway will be making his Major League debut when he takes the mound, which could happen during the twin bill given the pitching depth a doubleheader typically requires.

San Francisco also called up right-hander Matt Wilkinson from Sacramento to start Game 1 as the official 27th man for the doubleheader and optioned right-hander Spencer Bivens to Sacramento. No corresponding 40-man roster move was needed to add Lonsway, as the Giants had an open spot.

What happened

Lonsway, 27, was a sixth-round pick for San Francisco in the 2021 draft out of Ohio State. He has spent this season working between Double-A and Triple-A, posting a 57.7% groundball rate over 75 2/3 combined innings. The club announced the move prior to the doubleheader at Oracle Park.

The selection gives the Giants another left-handed option for a day when they will need to cover two full games. Wilkinson draws the start in Game 1, with Yunior Marte listed as the probable pitcher for Game 2 against Arizona's Merrill Kelly and Mitch Bratt, respectively.

Why it matters

The twin bill is the roster churn's natural habitat. The 27th-man provision allows clubs to add an extra arm for the day without burning an option on a player who might pitch an inning and return to Triple-A the next morning. Lonsway's selection, by contrast, is a standard 40-man call-up, which suggests the Giants see a role for him beyond today's games.

The grounder profile is the tell. A 57.7% groundball rate over 75 2/3 innings this season marks Lonsway as a contact manager rather than a swing-and-miss artist. He does not amass many strikeouts and does not throw with much velocity, per the club's announcement, which makes him a specialist in the oldest sense: a pitcher who gets outs on the ground and trusts his defense to convert them.

That skill set has a place in a bullpen, particularly one navigating the final month of a season that has long since turned to evaluation. The Giants are 59-84, 26.5 games back in the NL West and eliminated from the division race. They are 16.0 games behind the Wild Card cut line, ranked 11th in the National League. The doubleheader is an opportunity to see what Lonsway can do against Major League hitters without the stakes that would accompany a pennant race.

Left-handers who generate grounders at that rate are useful even when the fastball does not light up the radar gun. The pitch mix matters less than the result, and if Lonsway can keep the ball on the infield dirt, he has a case for sticking around. The Giants have an open 40-man spot, which means they did not need to clear space for him, and that suggests they had been planning this move rather than scrambling to fill a doubleheader roster.

The timing also matters. San Francisco is two days away from the end of August, which means the active roster will expand from 26 to 28 players on September 1. Lonsway's selection now gives him a few days to settle in before the roster crunch eases and the club can carry more pitchers without the daily calculus of who to option and who to keep.

The numbers

Lonsway has logged 75 2/3 innings across Double-A and Triple-A this season, generating a 57.7% groundball rate. The announcement did not include his earned run average, strikeout totals, or walk rate, but the grounder percentage is the headline figure for a pitcher whose profile depends on keeping the ball on the dirt.

The Giants are 59-84, fourth in the NL West and 26.5 games back. They have won one in a row heading into the doubleheader.

Where the club stands

San Francisco enters the twin bill with a 59-84 record, fourth in the NL West and eliminated from the division race. The Giants are 16.0 games behind the Wild Card cut line, ranked 11th in the National League. They have won their last game, a modest streak that the doubleheader will either extend or erase twice over.

After the Diamondbacks leave town, the Giants travel to Atlanta for a three-game series beginning Monday. Anthony Molina is listed as the probable pitcher for the opener against the Braves' Bryce Elder.

The final month of the season is an audition period for a club that has been out of contention for weeks. Lonsway is one of several players who will get a look in September, and his performance will help shape the bullpen depth chart heading into the offseason. The Giants have carried an open 40-man spot, which gave them the flexibility to add Lonsway without designating another player for assignment, and that flexibility will matter again when the roster expands in two days.

What we don't know yet

The announcement did not specify whether Lonsway will pitch in Game 1, Game 2, or both, only that he could very well appear given the pitching demands of a doubleheader. The club also did not say whether Lonsway will remain with the team after the twin bill or return to Sacramento once the 27th-man roster spot expires.

Spencer Bivens was optioned to Sacramento in a corresponding move, but the announcement did not detail his season line or the reason for the demotion beyond the need to clear space for Wilkinson and Lonsway. The Giants have not said whether Bivens could return when the roster expands or whether the option is a longer-term move.

The club also did not provide Lonsway's full season statistics beyond the groundball rate and innings total. His strikeout and walk numbers, along with his earned run average, were not included in the announcement, which leaves some uncertainty about how he has performed in the upper minors this year.

What to watch

Lonsway's debut, whenever it comes, will be the first test of whether his grounder profile translates to the Major League level. A 57.7% groundball rate is a strong foundation, but the announcement noted he does not throw with much velocity and does not amass many strikeouts, which means his margin for error is narrow. If he can induce weak contact and let his infielders do the rest, he has a case for sticking around beyond today.

The doubleheader itself is a showcase for the Giants' pitching depth. Wilkinson starts Game 1, Marte is listed for Game 2, and the bullpen will need to cover whatever innings remain. Lonsway is one of several arms who could be asked to bridge the gap, and his performance will help determine whether the club sees him as a September option or a player who needs more time in Triple-A.

The 27th-man rule is a useful tool for clubs navigating a doubleheader, but it also creates a decision point. Wilkinson could return to Sacramento after the twin bill unless the Giants choose to keep him on the active roster, and that choice will depend on how he pitches and what the bullpen needs. Lonsway, by contrast, is on the 40-man roster and does not have the same automatic demotion awaiting him, which gives him a longer runway to prove he belongs.

San Francisco has a month remaining in a season that has been over for weeks. The final stretch is about auditions, and Lonsway just got his invitation to the stage. Whether he sticks around will depend on what he shows in his first taste of Major League hitters, and the doubleheader is as good a place as any to find out.