DENVER -- Mac Williamson knows how many days it's been since April 24, 2018.

"It's been about 380 days," Williamson said when asked to reflect on his turbulent baseball journey since suffering a concussion on that date. "Last year was extremely frustrating for multiple reasons. ... It is definitely gratifying that I've been able to put it back together, somewhat."

The Giants called up Williamson from Triple-A Sacramento prior to Tuesday's series-opening 14-4 win over the Rockies at Coors Field, a day after he launched three home runs in Sacramento's 12-6 victory over Reno, including one that traveled over 500 feet.

He picked up right where he left off at Triple-A, starting in left field Tuesday and going 2-for-4 with a three-run homer.

Calling up Williamson was just one of a number of moves San Francisco made Tuesday, with the club also recalling infielder Donovan Solano and reliever Williams Jerez, optioning outfielder Mike Gerber, and designating infielder Yangervis Solarte and reliever Pat Venditte for assignment. Outfielder Gerardo Parra, who the Giants DFA'd last week, cleared waivers and selected free agency.

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.

Williamson was off to a great start when he was called up to the Majors on April 20 of last season, batting .316 (6-for-19) with three home runs in his first five games. But on April 24, then-Nationals outfielder Bryce Harper hit a fly ball down the left-field line in San Francisco that Williamson chased to the visitors' bullpen in foul territory. He took a tumble, slammed headfirst into the wall and suffered a concussion that wrecked the rest of his season.

Healthy once again when Spring Training arrived, Williamson set out to make the Opening Day roster, but struggled to a .237/.286/.322 slash line with one homer in 22 games. He was the last player to be cut before the regular season began, and because he was out of Minor League options, he was put through waivers, which he cleared before being assigned to Triple-A.

At Sacramento, Williamson hit .378/.459/.756 with nine homers in 23 games, culminating in Monday's prodigious power display. Meanwhile, the Giants could use all the offense they can get, entering play Tuesday ranked last in the Majors, along with the Indians and Marlins, with a wRC+ of 68. Left field has been a particularly unproductive position, from which the Giants have gotten a .517 OPS so far this year.

"We've talked a lot about how our plan with the outfield the entire offseason was about maintaining flexibility to give guys like Mac an opportunity to earn playing time, and earn their job," Giants president of baseball operations Farhan Zaidi said. "It didn't happen this spring, but it's happened now."

Williamson attributes his resurgence at the plate, in part, to an adjustment he made in his batting stance.

"I actually kind of stole it from Gerber a little bit," Williamson said. "I liked how his setup was, and how he was getting to his front side, and how he was balanced on every swing and take. We had a joke going on about that, about how I stole it from him."

"I thought he had a lot of movement early," said manager Bruce Bochy, who added that Williamson is the club's starting left fielder going forward. "A big stride, over-striding, the timing was a little off, getting into what they call launch position. So I think he's in a better position now."

Williamson was candid when speaking about whether this could be his last shot with the Giants, saying that's his assumption, though he doesn't think it's his last opportunity in baseball.

Zaidi said he "would not be that dramatic" about the possibility of this being Williamson's final chance with San Francisco, adding that he expects him to "get a good extended look" based on his history, and what he's done early this season at Triple-A.

San Francisco's roster flux has been indicative of the inability of offseason additions to pan out, particularly on offense. With the departure of Parra and Solarte, none of the Giants' offseason acquisitions to bolster the lineup remain on the club. However, Kevin Pillar, who was acquired from the Blue Jays in April, has shown some production, including a fourth-inning homer on Tuesday.

"We've taken some chances," Zaidi said. "I think it's fair as a front office, and for me personally, I haven't done the job of identifying the guys who can help us in that spot.

"A key for us this season, I think, is going to be adaptability and looking at different guys. We're trying to compete, but we're also trying to find guys who can be keepers for this organization, who are going to be here for a few years. We're kind of trying to walk that balance, and part of it is giving guys opportunities, but sometimes having to pull the plug before you get what really amounts to an appropriate sample look."

Additional notes

Jerez, the latest addition to San Francisco's bullpen, bolsters a relief corps that has seen very high usage of late, particularly in the last series against the Reds, where Giants starters surrendered 26 earned runs over 14 innings (16.71 ERA). The left-hander, who turns 27 later this month, posted a 2.40 ERA over 12 appearances for Sacramento. He made his first big league appearance of the season on Tuesday, pitching a scoreless inning with two walks.

Solano, 31, takes Solarte's place on the roster as a backup infielder. He hit .322/.392/.437 in 24 games for Sacramento this season.

Giants' Honorary Bat Girl to be honored

As part of Major League Baseball's annual Honorary Bat Girl initiative, the Giants have selected Ellen Shaler of Oakland as their honoree prior to San Francisco's Mother's Day contest against the Reds at Oracle Park.

Each Major League club had the opportunity to select an Honorary Bat Girl who demonstrated an extraordinary commitment to battling breast cancer. At age 44, Shaler was diagnosed with a fast-growing, non-invasive ductal carcinoma in situ (DCIS) in 2005.

Just after her 45th birthday, Shaler had her ovaries, uterus, and cervix removed prophylactically. However, her next mammogram revealed another DCIS spot in a different part of the same breast.

She then underwent seven surgeries over 20 months, including bilateral mastectomies as a preventive measure, followed by reconstruction. Shaler has teamed with the Susan G. Komen Foundation to raise more than $8,000 for cancer research in her mission to help others have access to the quality care she received.