According to Adam McCalvy they have to stay 10 days now after the most recent CBA but I can't find the particular rule where it states that. it appears you're correct. the source on mlb.com that i have been citing was from 2016. i wonder who pushed for this change. from a player's perspective, it may give a club pause in optioning a guy towards the end of august knowing that he's hands off for 10 days, but from the club's perspective, they have up to 15 guys to choose from to absorb the workload of that optioned player as soon as 1 september (plus any outside acquisition in late august). taylor williams will be burning his second option and will enter 2019 spring training with one option remaining. if under the previous collective bargaining agreement, he wouldn't be forced to burn that second option.