Honestly, I think this came more down to not feeling prioritized by KY.
If I'm Noah, I feel more concerned about the Mag fellow, than I do about the no-brainers like Berke & Maxim.
And I get why KY (& a good many coaches) would rather have Mag as a 3-4 in the rotation than they would Waterman.
Waterman's a good ball player & mismatch guy, but he is neither a reliable point-getter nor a very forceful player. Mag gives us a forceful player who might have as much defensive versatility as Noah (though he won't be able to match the bigger, non-athletic 5s like Noah could at times). He's not as reliable from deep as Waterman, but he puts a LOT more pressure on the rim.