- Bats Left, Throws Right
Joossens made his First Division debut in 2016 at age 18; he was 1-3 with a save and a 4.28 ERA for the Brasschaat Braves.  A late addition to the Belgian squad for the 2016 European Championship, he got into two games. Facing eventual Silver Medalist Spain, he relieved Jace Van Droogenbroeck in the 7th inning of a 11-1 mercy rule rout. He gave up a double to Jesús Golindano but then retired Richard Montiel, Jesús Ustariz and Lesther Galván in order. He did not fare as well against Bronze Medalist Italy. He relieved an even younger pitcher, Drew Janssen, in the 5th with a 8-0 deficit, two on and one out. He plunked Mattia Mercuri then walked Alex Sambucci on a full count to score one run. Another walk to Mattia Reginato made it 10-0. Alessandro Vaglio singled in another run. Fellow teenager Gregg Mareels relieved and let all the inherited runners score. He finished with Belgium's highest ERA (36.00) in the event. 
He played in the Collegiate Baseball League Europe in 2017, appearing for the Antwerp Cavaliers.  He fell to 0-2 with a save and a 8.40 ERA for the 2017 Braves.  He was 2-0 with a save and a 5.74 ERA in '18.