Success depends greatly on not tipping pitches, and perhaps that is never more true than on the change. Good batters will detect a difference in your delivery, so of course you can't throw a change-up by easing up on the gas or anything major like that. Maybe a Ted Williams can spot the different placement in the hand on a circle-change, but against human batters that or something similar seems like the way to go. I really enjoy reading these deeply introspective interviews with players. When I've asked old-timers on panels to "scout themselves as a player", 9 times out of 10 they'll say something on a par with "don't walk him, heh heh heh". And young players have an incentive not to say anything that might benefit an opponent, so I don't seem to run across a lot of interviews like this one. But it's great, and leads me to believe that current players are better students of the game than ever before, contrary to the narrative some grouchy fans would like to pass off.