Causation tends not to work this way, though it's an interesting premise.

I have no doubt that Jose ends up as one of the most influential players of his generation, both on and off the field. That said, the nature of secrets is that they get out. If it had not been Canseco, there would have been someone else that came along, who had the financial (or attention whore) incentives to have gone public with all this.

What Canseco seems to have known is the degree to which people were doping, especially the game's elite players.

Curt Flood had something to lose.

The sad thing about Curt Flood is that what he did really didn't have much effect on the player's winning their freedom, that was already in the works through the process that Marvin Miller set forward through labor negotiations. At that time, the commissioner handled all grievances between player and team, and Miller gently threatened to flood (no pun intended) Bowie Kuhn with dozens of grievances; Kuhn then agreed that an arbitrator (independant) should handle grievances. This is how the union got Hunter free-agency and also Messersmith when he played out his option year. Marvin Miller should be in the hall of fame. Flood just didn't want to play in Philadelphia, that had more to do with the suit than a sacrifice to benefit all players in the future.

While he is turning into one of the most significant players in baseball's history - it should be remembered, that it was an accidental happening in pursuit of padding his bank account.