concur w/ red and darnoc, however bobmeyer is spot on as well - if (for whatever reason - for instance, injuries - if a player is promised a start he expects to play and get that start if he is at 60% health or above, even though most people would still rest a player at 60%) anyway, if the player is below the magic number of % of starts, starting in the postseason counts towards his overall total, so it may help you meet the requirement, but is not itself required, if that makes sense...
If you have met your obligation (ie the kid is not letting you know he's ******) then promises can be discarded after the reg season.