That is valid, but one would expect either good numbers in net or good numbers in punts inside the 20 if either extreme were the case. For an above average punter, from an average punting distance, one would expect both net and inside the 20 stats to be above average.
One thing about the stats that nobody ever mentions: they all depend greatly on WHERE THEY ARE KICKED FROM! You're going to put a lot more inside the 20 punting from your 45 than from your 25, no matter how good or bad your leg is. On the other hand, a real boomer likes to have space. Suffice it to say, these numbers. moreso than almost any other positional stat, depend on how well your offense did before you even hit the field.