Kristaps Porzingis Steals Prop is currently Over/Under 0.5 (-148/+110).
The money has been on the Under as it opened 0.5 @ +112 before it was bet down to 0.5 @ +110.
FACTORS THAT FAVOR THE OVER:
The Golden State Warriors have played at the 2nd-fastest tempo in the NBA over the last 10 games while traveling, which ought to lead to increased possessions for the Celtics.