10 days remain until Athletics Opening Day at the Toronto Blue Jays on March 27, 2026. With Las Vegas on the horizon, this daily countdown tracks the best A’s players by jersey number.
Today, March 17, 2026, the number is 10.
Marcus Semien, No. 10
Marcus Semien is the best Athletics player to wear No. 10 because his Oakland run featured the clearest peak, the most total value, and the kind of every-day durability that defined an era. Semien spent six seasons with the A’s (2015-2020), moved from shortstop to second base later in his career, and became one of the franchise’s most important players of the late-2010s.
Semien also fits the series rule: his overall career value is elite for this number, and his A’s stretch is the separator. He owns 49.2 career WAR, and 20.0 of that came in Oakland. His best A’s season was 2019, when he produced 8.4 WAR and finished third in MVP voting.
Why Semien gets No. 10
Semien gets No. 10 because he wasn’t just a good A’s regular — he was a foundational player at a premium position who played every day and hit in the middle of the order. From 2015 through 2020, he gave the A’s stability up the middle and grew into one of the most complete position players in baseball.
There are other strong No. 10 options in team history, but none match Semien’s combination of peak season, multi-year impact, and franchise-defining presence in Oakland.
Career start and background
Semien was born Sept. 17, 1990, in San Francisco, Calif. He played at the University of California, Berkeley. He debuted in the majors in 2013 and arrived in Oakland ahead of the 2015 season, where he developed into a cornerstone player during the A’s late-2010s run.
Other notable No. 10s
- Marcus Semien
- Daric Barton
- Scott Hatteberg
- Ray Fosse
- Lefty Grove
Career check
No. 10 goes to Marcus Semien. He delivered star-level value in Oakland, highlighted by a monster 2019 season, and he wore the number long enough — and well enough — to make it his for this countdown.
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Dice City Sports editor Mark Hebert covers the Vegas Golden Knights, Las Vegas Raiders, Athletics, and UNLV baseball and softball. He has 24 years of journalism experience, is also a senior reporter at Exhibit City News, and previously covered the Dallas Stars and Texas Rangers. Follow him on X or connect on LinkedIn.
