Not all punts are created equal, and nor are all punters, or for that matter, special teams coordinators. All of those variables, plus the opponent, the weather, and the coverage unit all factor into a team’s approach to any given punt, on top of the game situation and field position.
That’s why it’s wise not to read everything into pure gross averages, because teams who don’t move the ball as well are likely to have more long punts. Conversely, teams who do move the ball are more likely to be punting from near midfield or so.
A punter averaging 38 yards per punt could be better than one averaging 48 if you’re not contextualizing the numbers.