In regard to the proposed 20-second pitch clock rule:

if i was a base stealer i would wait until 19 seconds, then take off.

is this a weakness of the pace-of-play clock rule?

we have been watching how Joe Maddon likes to send his runners when there is a breaking-ball count (ie. the hitter has seen a good sequence of fastballs and an educated guess is that an off-speed pitch is coming).

so we will end with some math:

off-speed count + 19 seconds = i gotta steal

pitch clock  + larger base = runner advantage