95% its the pilot.
Yes. In other words, the guy behind you has to be a nincompoop.
I'd be able to shake off a Zero in a 190 flying low and slow so long as the guy behind me is a nincompoop. However, get a more maneuverable plane with a pilot at least as good as yourself latched behind you and nothing will work. Roll, loop, flat scissors, rolling scissors, desparate jinking, +Gs, -Gs, one-trick gear dropping, flap floppin'.. etc etc. Nothing works. The guy behind just chops throttle, and matches every move and blasts you outta sky.
It's just the way things are.