If your player did not play, he will be voided.
NFL- The player does not play a snap
NBA - The player plays zero minutes
NHL - The player has zero time on ice
MLB - A hitter is not in the starting lineup or does not record a plate appearance. A pitcher does not throw a pitch. (For Example: a player who did not start but made a plate appearance/threw a pitch would still be voided)
If you made a multiple-pick entry and a player did not play, the pick affected would be voided and the selection would reduce in size. For example, if you had a seven-pick entry, then it would turn into a six-pick entry if a player does not play for any reason.