So, basically whoever came top is COY? Not saying some (most?) of those guys aren't deserving, but it just looks like you've taken it straight from the ladder.
My nominations, not just based on wins & losses, but on improvement & overachieving as well:
U10 boys - Martin Hinton (Sturt)
U12 boys - Michelle Parker (Norwood)/Daryl Crump (South)
U14 boys - James Murphy (Eastern)/Michael Humphrys (Sturt)
U16 boys - Andrew Jantke (Centrals)
U18 boys - Adrian Hodges? (Southern Tigers)
Reasoning:
U10's - have killed everyone, probably won't be any arguments with this one.
U12's - Not sure any of the top 3 teams have a deserving coach for this award, and I think these two sides have improved throughout the season. Honourable mention to the Woodville coach for managing to get 2nd place at state champs.
U14's - Murphy has done a good job with the Eastern boys & had a decent Classic result, however, Sturt has won both Summer & State Champs, so I think Humphrys has to be in there as well.
U16's - Jantke has done a very good job with his group, to the point where they pushed a top 3 side (Norwood) to within 5 points at state champs. Was business-like in dealing with the "poaching" incident.
U18's - Southern have definitely over-achieved for the season. I think Hodges is coaching them now, though I could be mistaken. Seemed to gel after losing a "star" player to another club.
Girls to possibly come later, though I must confess to knowing less about that side of the competition.