Walsh said he was saddened by Van Ass' sudden ouster just five months into the job following an altercation with Hockey India president Narinder Batra.
"This (Van Ass' sacking) is potentially destabilising for the Indian hockey team," Walsh told PTI in an interview from Perth, when asked about the current mess in Indian hockey just a year ahead of the Rio Games.
Van Ass's predecessors Jose Brasa, Michael Nobbs and Walsh - all of whom were hired by Sports Authority of India on the recommendations of HI at hefty salaries - also left the country on an unceremonious note.
Walsh, under whose guidance India sealed a direct ticket to next year's Olympics after winning the gold in the Incheon Asian Games, however feels the Sardar Singh-led side has the potential to create a magic in Rio.
The former coach, though, was surprised by the disciplinary issues raised against Gurbaj Singh and said the experienced midfielder is a key player for India going into the Olympics.
"The team has enough time to reset direction for the Olympics in Rio. (But) it surprises me that issues are again being had with Gurbaj. I found him to be an outstanding component of our team. Without key players like Gurbaj, the task becomes seriously more difficult," Walsh said about Gurbaj's omission from India's upcoming Europe tour on disciplinary grounds.