SAN FRANCISCO -- The Mac Williamson era appears to be over.

The Giants designated Williamson for assignment for the second time this season and promoted outfielder Mike Yastrzemski from Triple-A Sacramento on Saturday. Yastrzemski, the grandson of Hall of Famer Carl Yastrzemski, started in left field against the D-backs in his Major League debut.

Williamson, 28, batted .118 with a .407 OPS and 18 strikeouts in 51 at-bats this year. A third-round Draft pick of the Giants in 2012, Williamson flashed tantalizing power in the Minors but struggled to produce in the Majors, batting .207 with a .641 OPS and 14 home runs in 135 games with the Giants.

He appeared poised for a breakout season last year before suffering a career-altering concussion after stumbling over the bullpen mounds and crashing into the left-field wall while chasing a fly ball.

"Very tough conversation, to be honest," manager Bruce Bochy said. "I don't know if I've pulled for a player as hard as I have for Mac. Especially with him going through waivers, going back down there and getting his game back. He worked hard to get this opportunity, but it got the point where with his struggles, we just need some help. It was not an easy one."

The Giants already designated Williamson for assignment once at the beginning of the season after he failed to make their Opening Day roster. If he clears waivers for a second time, he will have the opportunity to become a free agent and sign elsewhere.

"I don't know what's going to happen, but he's got to keep pushing whether it's here or somewhere else," Bochy said. "He'll get another opportunity. Hopefully, it works out well for him."

When a player's contract is designated for assignment -- often abbreviated "DFA" -- that player is immediately removed from his club's 40-man roster, and 25-man roster if he was on that as well. Within seven days of the transaction (it was previously 10 days), the player must either be traded, released or placed on irrevocable outright waivers.

Yastrzemski, 28, became the ninth player to appear in left field for the Giants this season. Acquired from the Orioles in exchange for pitcher Tyler Herb in March, Yastrzemski was hitting .316 with a 1.090 OPS and 12 home runs for Triple-A Sacramento this year. His 12 home runs are already three shy of his most in any year as a professional -- he hit 15 across Double-A and Triple-A in 2017 in the Orioles organization.

"I'm just ecstatic," said Yastrzemski, who went 0-for-3 in the Giants' 10-4 loss, scoring a run on a bases-loaded walk after being hit by a pitch to start the seventh. "It's a lifelong dream to be here. To finally step foot in a big league clubhouse is something special."

Yastrzemski said he called his grandfather and delivered the news while making the drive from Sacramento on Saturday morning. Yastrzemski said his grandfather currently lives in Boston and is "not much of a traveler." His wife and mother, however, were in attendance for his debut.

Bochy said the left-handed-hitting Yastrzemski will platoon with Tyler Austin in left field for now. Yastrzemski has played 703 career Minor League games from 2013 through this year, posting a .263 average and .782 OPS.

"He's getting his chance here," Bochy said. "He spent some time in the Minor Leagues, and he's put together a nice year. He's played some great baseball down there in Sacramento. He's earned this callup, so he'll be in left field quite a bit. He's got good plate discipline, he's got some pop. He's just a baseball player. I look forward to watching him. I haven't seen him play except for a little bit of video."

Gott to IL, Rodriguez recalled

The Giants placed right-hander Trevor Gott on the 10-day injured list with a right forearm strain and recalled right-hander Dereck Rodriguez from Sacramento on Saturday. The Giants needed coverage in their bullpen after their relievers combined to pitch 13 1/3 innings over the previous two games.

Gott, 26, has been one of the most pleasant surprises of the season for the Giants, recording a 3.00 ERA with 25 strikeouts over 24 innings in 2019. He allowed three runs over two-thirds of an inning in Friday night's 18-2 blowout loss against the D-backs.

Pitch, Hit and Run results

The Giants hosted a Pitch, Hit and Run event on Saturday morning at Oracle Park, giving the top 12 baseball and top 12 softball qualifiers from Northern California the opportunity to compete for a spot in the National Finals during the 2019 Major League All-Star Week in Cleveland.

Here are the champions from each team:

For the 7- and 8-year-old Softball Division: Renee Dragseth from Rocklin

For the 7- and 8-year-old Baseball Division: Ivey Jackson from Stockton

For the 9- and 10-year-old Softball Division: Desiree Shoblo from Alameda

For the 9- and 10-year-old Baseball Division: Tristann Trego-Cardenas from Monterey

For the 11- and 12-year-old Softball Division: Katelynn Larson from Rancho Cordova

For the 11- and 12-year-old Baseball Division: Ethan Roche from Los Gatos

For the 13- and 14-year-old Softball Division: Isabella Fong from Pacifica

For the 13- and 14-year-old Baseball Division: Raymond Olivas from Stockton