Johnathan Magnus Polonius
- Bats Right, Throws Right
- Height 6' 1", Weight 160 lb.
Polonius hit .370 for Genesee Community College in 2011 and was named the school's Male Athlete of the Year.  The Cleveland Indians took him in the 30th round of the 2011 amateur draft, one round before Michael Roth, but he opted not to sign. He transferred to WVU and batted .306/.386/.480.  The San Francisco Giants signed him as an undrafted free agent.
He began his pro career with the 2012 AZL Giants, hitting .300/.378/.408 and stealing 7 bases in 7 tries, scoring 25 runs in 32 games. He fielded .928 as their primary shortstop. He split 2013 between the Salem-Keizer Volcanoes (.270/.333/.372 in 39 G) and San Jose Giants (.221/.286/.316 in 26 G), now serving as a utility infielder, the role he would fill for the next several years in the Giants chain. He hit .257/.342/.336 for the '14 Augusta GreenJackets. In 2015, he batted .204/.248/.317 for San Jose.
In 2016, he played for Augusta (.218/.283/.282 in 34 G), the AZL Giants (.400/.462/.600 in 10 G) and the Richmond Flying Squirrels (2 for 6, 3B, BB), going 12-for-17 in steal attempts. The next year, he appeared for San Jose (.265/.327/.373 in 36 G) and the Sacramento River Cats (2 for 5, 3B, 2 R, RBI). He ended his time in the US with San Jose (2 for 16, 2B, BB), Richmond (.222/.304/.309 in 37 G) and Sacramento (4 for 19, 2 2B) in 2018.
Polonius went to the Eastern Hemisphere for 2019, signing with Unipolsai Bologna. He was 6 for 15 with a double, triple, four runs, three walks and four RBI when they won the 2019 European Champions Cup.  In the 2019 Serie A1, he hit .316/.387/.570 with 5 homers and 24 RBI in 20 games. He was 10th in the league in slugging, 3rd in RBI (after Jose Flores and Sebastiano Poma), 10th in total bases, tied Segundo Paolini for 2nd in steals (8), tied Osman Marval for the lead in sacrifice flies (3) and tied for 4th in dingers.  He was 2 for 11 with a double, two runs and two walks when Bologna swept the 2019 Italian Series; he scored their first run, singling off Carlos Quevedo and scoring on a fly from Alessandro Vaglio. 
He then debuted for the Netherlands national team, splitting short with Sharlon Schoop in the 2019 European Championship. His went 4 for 12 with two walks, three runs and a RBI while fielding .889 entering the Gold Medal Game. In the finale, he started at short and hit 9th, going deep off Luis Lugo in a 5-1 win over Italy.  In the 2019 Europe/Africa Olympic Qualifier, he was 3 for 14 with a walk, double and a run as the main shortstop for the Netherlands. He handled 15 chances error-free. The Netherlands did not win a spot in the 2020 Olympics but stayed alive for the next qualifier (which, like the Olympics, wound up being delayed due to the COVID-19 pandemic).  He did not remain with the team for the 2019 Premier 12, Ray-Patrick Didder replacing him at SS (interestingly, Didder would replace him with Bologna for 2020 as well).
He signed with Dutch powerhouse Curaçao Neptunus (based in Rotterdam, not Curaçao, whose government sponsored the team) for 2020 but that season was delayed by COVID-19. He hit .367/.462/.532 with 27 runs, 22 RBI and 7 steals (caught once) in 19 games, fielding .949. He was 4th in average (between Dwayne Kemp and Kenny Berkenbosch), 8th in slugging (between Darryl Collins and Ruendrick Piternella), 7th in OBP (between Denzel Richardson and Stijn van der Meer), led in runs (four ahead of Richardson), was 4th with 29 hits (between Richardson and Tyriq Kemp), ranked 4th in RBI, tied for 4th in homers (3), was 5th with 42 total bases (between Kalian Sams and Gilmer Lampe), ranked 4th in swipes, was 3rd in assists (58), tied for 9th in errors (5) and tied Duco Nuijten for 5th in double plays (16).  He was 1 for 9 with a run in the 2020 Holland Series when the Series was cut short due to COVID-19 restrictions, costing him a chance at titles in two countries in two years (Neptunus was down 2 games to 0 at the time, though).