Yeah, I defer to others on Lowry/oscar's history of defensive systems. I just know that the difference between Frankball and Bruceketball on-ball pressure, hedging on screens, help expected/given is night and day. Is that all poor execution? I doubt it.
I think the intent of #bruceketball is ball pressure without getting beat as much AND without the backdoors/open lay-ups that #frankball sometimes gave up. #brucketball pressure is more predicated by creating TOs with steals because of ball pressure combined with "more sound" position with off the ball defense. #frankball pressure was predicated by overwhelming ball handlers, and while that occasionally led to lay-ups/backdoors, more often than not it also led to teams throwing the ball out of bounds, etc.
I think both defensive systems rely on a rim protector, but #frankball left that guy on an island more than #bruceketball does.
That would be my explanation of the differences.