Subsequently, he moved to Germany's Bundesliga, playing for Arminia Bielefeld and then Hertha BSC. Although he did not receive a lot of playing time at Hertha, he helped the club win the DFB-Ligapokal two times during his time there. In 2003, Maas moved to the 2. Bundesliga club MSV Duisburg. After two seasons, he returned to the Netherlands, helping newly promoted Heracles Almelo avoid relegation and stay in the Eredivisie. He then had a second stint at RKC Waalwijk from July 2008 until June 2009, when he retired.
Managerial career
Following the departure of Peter Bosz to Maccabi Tel Aviv on 4 January 2016, Maas, who had been Bosz's assistant, was appointed interim manager of Vitesse.[5] On 8 May 2016, the final day of the 2015–16 season, it was announced he was relieved of his duties.[6]
On 17 June 2016, Maas was appointed manager of SC Cambuur, replacing Marcel Keizer who had left the club after their relegation to the Eerste Divisie.[7] Four months later, on 15 October 2016, Cambuur announced that they had sacked Maas, as the club was in fourteenth position after ten league games.[8]