Trip averaging has to do with the duty period minimum of 4.5hrs. That why you can have a 2 day trip with day one flying 7hrs and day two flying only 2hrs. It averages out to 4.5 per duty period instead of getting 7hrs and 4.5hrs. Averaging is pretty industry standard only its calandae days not duty periods like we have.

Block or better has nothing to do with averaging.