Hafey did get Collingwood to four GF's in six seasons. Given they didn't play in a GF for six seasons pre-Hafey and seven seasons post-Hafey, an alternative view might be that his methods worked.
given that tapering is a well known training strategy nowadays in all sports, I call bullshit on that theory.
We're off topic and yes his fitness regime certainly worked. But it hindered when it mattered.