My personal opinion is that Petersham need to win the top 2 games to be considered for promotion at this point.
Yes, Petersham are club champions, but they haven't had the lower grade depth in a competition that was designed to give all but 2 teams the chance at premierships. That, for me, is a missed opportunity. As much as it pains me to say having an affinity for them as neighbours (kinda), Petersham have been the top club this season in many ways, but UNSW have been right on their tail when behind them AND miles ahead of them in 3s and 4s.
UNSW are the team I believe should go up assuming they don't s*** the bed on Saturday. Look at their performance top to bottom - EVERY grade made finals and only 1 grade (ironically, their lowest) missed the Grand Final. If you want to look at a club that will be competitive in Div One, where you'll need to field an extra side, you have to look at a team with 5 already strong teams ready to go.
The only thing that will hurt them on Saturday is that they have to field 60 fresh players in consecutive games - are they going to have any fresh reserves that wouldn't be starting in a lower grade? It's an odd situation for sure, but that comes down to Club Championships points multipliers rather than any perceived gulf in performance.