Ehh, he was just a lot better back then. He had a lot more lift and he hit more contested shots. 16/17 Crowder hit 40% of his open 3's. 18/19 Crowder hits 33%.When folks say the "Boston version of Crowder" they really mean the 2016-17 version of Jae Crowder. That year he started every game and played the majority of his minutes with Isiah Thomas - who had defenses scrambling all season.
Statistically that season was probably an outlier - his other two seasons with Boston are pretty much on par with how he's performed this year. So basically what we've seen is a regression towards the mean.