Anyone guess which coach had a 61% win ratio with Leeds, and is now enjoying a 93% win ration? Anyone?
Sorry but quoting win percentages everywhere is a fundamentally flawed argument.
It is one indicator.
Brian Mac had a 37% win percentage at London before joining Leeds, and we all know what happened then.
How does the coach relate to media and sponsors? How do they relate to the key leaders in the team? What style of rugby do they promote? Do they give youth a chance, and give them the protection and support they need? Are they honourable and in line with organisational values? Technical v emotional?
So many components make up a good coach, and unless you had different coaches operating at the same time with exactly the same players and fixtures, it's extremely difficult to compare.
Coaches are also human and change/develop over time, it's not even a fixed quantity.
There are a million different factors which support organisational success/winning trophies, it's far more complex than previous win ratios over timescales which suit one point of view.