[citation needed] He attended Lower Columbia College in the United States.
[citation needed] Walsma debuted in the Hoofdklasse in 2005 and went 1-6 with a 5.11 ERA, walking 38 in 44 innings for the Amsterdam Pirates; he was 5th in the league in free passes.
[citation needed] In 2007, Walsma was 1-2 with a save and a 7.62 ERA for Amsterdam, with 19 hits and 13 walks in 13 innings.
Walsma was added to the Dutch national team for the 2008 Haarlem Baseball Week.
[citation needed] He then was selected by coach Robert Eenhoorn in the team that represents the Netherlands at the 2008 Summer Olympics in Beijing.