Is there any way to change a starting pitcher once he has been assigned the start and given the ball. I am in playoffs and my number 4 starter is slated to start, but my number 1 pitcher is healthy and ready. I was thinking of switching but did not know if this was possible. Thanks!!

It's not possible.

You have two options:

1) Tandem him with your desired starter and reduce his pitch count to the minimum of 40 pitches. He might pitch into the third inning before being replaced by the tandem B pitcher.

2) Move him to the bullpen, change his pitch count to 5, and set your desired starter as LRA and be sure that the LRA is the only pitcher eligible to enter in the first inning. The guy with the ball will still start, but likely would only face one batter before being removed.

Either way, it's probably good form to let your opponent in on what you're doing. Otherwise, it could come across as an underhanded ploy.

This is really helpful, thanks. I'm up 2=1 in 5 game so I think I'll just reduce pitch count a bit and leave my 1-2 starters for hopefully the next round. Appreciated the insight!

Also could set pull rating to a 5.

the third option is "designate for assignment", without waivers. It moves the player to limbo and gives the ball to the next starting pitcher in sequence, HOWEVER it also removes him from the playoff roster, which makes him ineligible for the rest of the round. If you do win the series, you are eligible to add him back to the 40 and back to the playoff roster in between rounds

Thanks Pjfoster, that is a really good thought for when you get caught in a tough situation.