Ajax chief executive Edwin van der Sar has admitted that Antony's move to Manchester United was difficult to take.
The Dutch club were determined to keep hold of the winger, who went on strike in an attempt to force through a move.
Eventually Antony ended up moving to Old Trafford after an offer of £86million was made.
Ajax also lost defender Lisandro Martinez to United and van der Sar feels that both players should have stayed for another year.
As reported by The Times, Van der Sar, who played for United between 2005 and 2011, said: 'It was our opinion they should stay for another year.