My series calculator is based on performance from the last 5 regular seasons and last 10 postseasons.
EAST
Miami vs. Milwaukee: 99.8% Heat
Spoiler:
NYK vs. Boston: 72.8% Knicks
Spoiler:
Indiana vs. Atlanta: 78.4% Pacers
Brooklyn vs. Chicago: 64.9% Nets
Spoiler:
WEST
OKC vs. Houston: 91.3% Thunder
SAS vs. LAL: 96.6% Spurs
Spoiler:
Denver vs. GSW 85.9% Nuggets
LAC vs. Memphis: 78.4% Clippers
Spoiler:
I'd agree that Chicago and Boston are the most likely teams to spring first-round upsets.