This makes zero sense as a metric. Were Hagan and Stuart the best for winning the comp in their first season?
It speaks a bit about their ability to extract the best out of a squad, with "limited" resources, in a short period of time.
I never argued that Cleary was the best, because he took the Warriors to a Grand Final in 5 years; my argument was that he clearly has some ability as a coach, because he took a team who - by, and large, throughout their existence - have been the dictionary definition of "inconsistent" to their second ever Grand Final.
I've heard a lot of, "Bennett was won nothing in 11 years, same as Brad", and, "Cleary had crap results for the first half of his career."
I don't believe that on-field results are the only indicator of the quality of a coach, and Arthur certainly ticked some plusses - though he had plenty of recruitment fails, he did get very good football out of Blake Ferguson, Danny Wicks, RCG, etc. -, but they are certainly an indicator of whether a coach is capable of winning a Premiership, which should be the ultimate goal of any coach.