I'm not sure the books have compensated for the Celtics no longer playing the 76ers, who did really well defensively on him, and how well Jaylen has played vs the Heat.
He's covered this line in every single game this year vs Miami averaging 41.25 points, rebounds and assists per game including 36 PRA in game 1 on a bad shooting night. In the 3 games prior, he's dropped 37, 26 and 28 vs Miami with (on average) less minutes. I'm expecting him to play as much as possible in game 2 after dropping game 1 to cover this line easier than he did in the first game.
I'm expecting Jaylen to play a big part in this series and continue his uptick from all categories vs a Heat team that has surprisingly had high scoring games vs the C's.