Seems Danny Amendola hated playing for Bill Belichick ... 'cause he called the Patriots coach a "principal" with a "principal's office" -- and even insinuated he didn't want to play hard for him.
It all went down on the Barstool Sports Comeback SZN Podcast ... when the Dolphins wideout was trying to compare his new coach Adam Gase to B.B. -- and he couldn't find enough differences.
"It's almost like coach Gase is one of the guys, one of the boys," Amendola says.
"And you want to fight hard for your boys.