His time at the club was marred with off-field dramas, most notably surrounding former Reds captain Travis Dodd who moved to Perth Glory.

Imports brought in by Coolen such as Evgeniy Levchenko, Ricardo Da Silva and Andwele Slory failed to make an impact.

[5] After a poor start to the 2011/2012 season, it was announced on 18 December 2011, that Coolen would be replaced by former Adelaide United coach John Kosmina.

[9] In August 2016, Coolen left his post as Academy boss at PEC Zwolle to join Fred Rutten as his assistant at Al Shabab in Dubai.

[1] On 21 October 2023, Feyenoord announced that at the end of the 2023-24 season Coolen would leave the club, due to differencing views on vision.