It don't think it has to be a called third strike. Can't it be a swinging strike three also?

And the catcher doesn't have to be charged with a passed ball. The batter can strike out on a wild pitch.

AS far as the rosters go, there are always 40 men on the roster. But only 25 are eligible to be on the parent team at any one time.

If a team wants to send a player to the minors (assuming he has "free" options left), they are free to do so as long as they replace him with someone from the 40 man roster.

If they want to replace him with someone not on the roster, they must first clear roster space for him by dropping a player from the 40 man roster, and that player must clear waivers.

I can't fully explain it, but there are certain benefits that the parent team has with respect to the players that they control on the 40 man roster.

One example is the Rule 5 draft. Players who have a certain number of years in the minors and who are not on a team's 40 man roster, can be drafted for a nominal cost by another team