I've run an update on Elo and Trueskill to reflect the tiers teams play in. Open has the lowest Elo and Trueskill, Mid's are unchanged, High has been given a boost and Prem has also been given a boost.
It's possible that these changes are a little strong, I'm hesitant to have all High teams rated above Mid teams when some of them are certainly weaker but I have to update the tier as a whole and in a comparison of overall win/loss rate between the two divisions the change is justified.
This now gives teams in lower tiers more ranking point incentives to take on teams in a higher tier.
Trueskill is a more complicated consideration because of it's uncertainty element, I've boosted those ranks but we'll have to see how that artificial change plays out over time.