I understand quite well the distinction between marginal rate and average rate, thank you.
What I am telling you is that before I ever get to take a penny out of my tIRA, we will be in the 22% bracket due to pensions and SS. Yes, the average tax rate we pay will be less than 22% due to the fact than some income is taxed at 10% and some at 12%, but there is literally nothing I can do to prevent our tIRA withdrawals from being taxed at 22% or more. Even taking out the amount I plan, at any reasonable rate of return I will never reduce my tIRA balance before RMDs hit. In fact, it likely will be 50% higher than when I start.
So, yes, I am certain I am getting the best rate by converting now.