I believe that whatever Mr. Chappel has said is correct. Currently, Ganguly is not in good form and he is unfit to lead Indian team. It is true that Indian team is most successful under him. But if you see the greatest captains like Steve Waugh, Mark Taylor etc. has to go when their team is still winning matches. If the player is out of form like Ganguly i.e. for a long time of 1 year, he should take sanyas from cricket.
Chappel has cultivated sense of insecurity in the team that unperforming player will go. But this is good for team. Players like Harbhajan, Zaheer, Yuvraj etc., are supporting Ganguly because they know that if they perform badly for a long time, other youngsters will replace them.
PS: Ganguly should go. It means Mr. Mahendra has lied & Chappel is right.