Johnathan Mackensey Williamson
- Bats Right, Throws Right
- Height 6' 5", Weight 240 lb.
- School Wake Forest University
- High School Wake Forest-Rolesville High School
- Debut September 23, 2015
Outfielder Mac Williamson began playing in the San Francisco Giants minor league system in 2012 and made his big league debut at the end of the 2015 season.
Mac was a star fastball pitcher while in high school. In 2006, he went 2 for 8 with two runs and three RBI for a US team team that won the COPABE Youth Pan-Am Championships. Baseball America rated him the top pitching prospect in North Carolina during high school. He hurt his shoulder, though, and had surgery, missing his freshman year of college in 2009. When he returned, he was an outfielder.
He hit .279/.355/.464 for Wake Forest in 2010. In 2011, the redshirt sophomore homered 12 times and batted .273/.368/.493. He was originally drafted by the Boston Red Sox in the 46th round of the 2011 amateur draft, but he did not sign. The next year, he produced at a .286/.396/.589 clip for Wake Forest and hit 17 homers in 53 games, driving in 52. He tied Ryan Mathews for the Atlantic Coast Conference home run lead and was 8th in RBI. He made All-Conference in the outfield alongside Mathews and James Ramsey. He did ink a contract after being drafted by the Giants in the 3rd round of the 2012 amateur draft. He was taken a couple picks after pitcher Onelki Garcia. He was the only position player the Giants took in the first eight rounds. The scout was Jeremy Cleveland.
With the AZL Giants (3 for 17, 2 HR, 2 BB) and Salem-Keizer Volcanoes (.342/.392/.596, 25 RBI, 7 HR in 29 G) in 2012, Williamson hit .321/.375/.588 with 9 home runs and 32 RBI in 33 games. He tied for 10th in the Northwest League in dingers despite his limited playing time there. In 2013, he hit .292/.375/.504 with 25 home runs, 89 RBI, 94 runs scored, 31 doubles, 10 stolen bases and 15 outfield assists in 136 games for the San Jose Giants. He was on the California League leaderboard in runs (5th, between Scott Schebler and Kevin Rivers), home runs (tied for third with Michael Snyder), RBI (8th, between Schebler and O'Koyea Dickson) and total bases (262, 4th, between Alex Yarbrough and Zach Borenstein). He did not make the All-Star team as Schebler, Andrew Aplin and Travis Jankowski were picked as the outfielders. Among Giants farmhands, he ranked 1st in runs (15 ahead of Gary Brown), 3rd in doubles (behind Devin Harris and Javier Herrera) and led in both homers (2 over Harris) and RBI (5 over Harris).
Williamson made his debut with Giants at the end of the 2015 season, when he hit .219 in 10 games. He saw more action in 2016 mainly due to an injury to regular right fielder Hunter Pence, and hit .223 in 54 games. He showed good power with 6 homers and 3 doubles in 112 at-bats. However, he only had 68 at-bats in 2017, hitting .235 with 3 homers, even though the team finished in last place and otherwise used the opportunity to give some younger players a look. At 26, though, he was no longer considered a prospect, and the fact he hit just .244 with the Sacramento RiverCats that year (although he displayed solid power there as well, with 21 doubles and 14 homers in 94 games).
He was back at Sacramento at the start of 2018 and started off on a tremendous hot streak, hitting .487 in his first 11 games. He was called up to San Francisco and quickly went on a homer run-hitting binge: he homered in his first game on April 21st, and then again in back-to-back games on April 23-24. The Giants won 4 of the first 5 games he started in place of an injured Pence (who had by now been moved to left field), giving the chance for Mac to become a bit of a folk hero in the Bay Area. He attributed part of his success to working out with hitting guru Doug Latta, the same man who was credited for turning Justin Turner into one of the most feared hitters in the majors. Latta completely remade Williamson's approach at the plate, working on his launch angle and trying to use his natural athleticism to transfer more power to his swing. The power surge didn't last though, as he hit just .213 with 4 homers and 11 RBIs in 28 games and was soon back in the minors. He hit .269 in 52 games for the RiverCats, with 13 homers and 44 RBIs. In 2019 he hit a scorching .378 with 9 homers in 43 games to get another look in San Francisco, but he completely failed to hit in the majors, with a .118 average in 15 games. His last two games were particularly brutal as on May 24th he went 0 for 5, striking out all 5 times against the Atlanta Braves, then the next day was 0 for 4 with 3 more Ks and was designated for assignment as Mike Yastrzemski was called up to take his place.
- Jorge L. Ortiz: "'You only get one career': Giants' Mac Williamson breaks out after big-time changes", USA Today Sports, April 25, 2018.