Nilsson became a free agent in the offseason following 1999, but opted not to sign with any MLB teams because of his desire to play for Australia in the 2000 Olympics.

[1] Nilsson was made a Member of the Order of Australia (AM) in the 2019 Queen's Birthday Honours in recognition of his "service to baseball as a player, coach and mentor".

[citation needed] Nilsson was signed by the Milwaukee Brewers in January 1987 at the age of 17 as an amateur free agent.

[4] Back in the ABL, Nilsson batted at .400 with the Daikyo Dolphins, only averaging behind fellow Brewers player John Jaha.

[5] He returned to the US at the age of 22 with the El Paso Diablos in AA batting with an average of .413 and was promoted to the AAA Denver Zephyrs before the end of the season.

Baseball America named Nilsson the league's #4 prospect after Rodriguez, Royce Clayton and Raúl Mondesí.

After performing below par in the 1992–93 ABL season, Nilsson was the most frequently used catcher for the 1993 Brewers, but due to injury problems, had rehab stints in the minors.

Milwaukee had originally requested that Nilsson be returned to the team in time for spring training but they later decided to let him stay for the playoffs.

He helped Brisbane to an upset win over the Sydney Blues for the championship; he formed a battery with his brother Gary for the final inning of the last round.

Despite being a part owner of the team, Nilsson came to regret his five-year deal with Waverly as he missed his hometown of Brisbane and tried to negotiate a way out of the contract.

The dispute lasted six months with the Reds finally coming to the agreement he would play out the rest of the 1995–96 ABL season before returning to Brisbane.

Although knee surgery cut his season short, he guided the team to the finals with a batting average of .420 which, had he played enough games, would have led the ABL that year.

He led the Olympics in average that year, 151 points ahead of runner-up Doug Mientkiewicz as well as also leading in both slugging and OBP.

[17] He returned to playing baseball that year for Telemarket Rimini in Serie A1 in Italy, where, although only hitting .280, he ended up slugging at a league-high of .920 and had an OBP of .561.

He entered the Hall of Fame with swimmer Ian Thorpe, Winter Olympics gold medalist Alisa Camplin, rugby league champion Allan Langer, tennis player Mark Woodforde, Australian football and media identity Lou Richards, and swimming coach John Carew.

[24] Nilsson was invited by Brisbane Bandits CEO Mark Ready to manage the team for the 2014 Australian Baseball League season.

Brisbane went on the beat the Adelaide Bite in the preliminary final and advanced to take on the Minor Premiers the Melbourne Aces in the Championship Series.

In 2018, following three consecutive ABL championships with the Brisbane Bandits, Nilsson was announced as manager of the Australian national baseball team.

[26] In 2021, Nilsson was named as the bench and hitting coach for the Lake Country DockHounds of the American Association of Professional Baseball.