But the USA lower leagues are a bit of a mess. Constantly changing the structure, new teams coming in and others folding or moving to new leagues like the MLS Next Pro. That's where most the MLS reserve teams now play, like Trevor Zwetsloot's New England Revolution II.
So surely that means alot of the young talent on the fringes of MLS has moved out of the USL Championship to this new MLS Next Pro comp. Diluting the talent level in the USL. The MLS Next Pro has also introduced a gimmick, with pen shootouts if is a draw in NT. Never a great sign for a serious football comp.
The 27 team USL Championship like all US leagues (and ALM) has no pro rel. This means that by mid season some of the lower table sides quickly have nothing to play for. So I'm guessing quality of games for those particular teams involved could be questionable as they start experimenting early with an eye to the following season etc. There is 14 teams in Eastern Division, and 13 in the Western Division.
https://us.soccerway.com/national/united-states/mls-reserve-league/2022/regular-season/r67284/I see that the quarterfinals of US Open Cup consists of 7 MLS teams and only 1 from a lower league (Omaha from USL League One). This despite MLS teams not taking the low prestige Cup comp that seriously, often running out reserve players. So suggests a bit of gulf between MLS and lower leagues.
Also guys like Musa (briefly with Minnesota), Collier (3 seasons, for 1 goal at Chicago) and Kyle Adams (very briefly at Houston) have been signed to MLS teams from the USL. None of them made the cut in truth. Did read an article a year or so ago, that with MLS clubs the USL has a bit of a stigma, is not rated, and clubs prefer to draft college youngsters, or sign foreigners (mostly Latinos).
The college youngsters then mostly loaned out to USL affiliate clubs, or now I guess they are playing in MLS Next Pro for MLS reserve teams.
Lastly hopefully Danny Hay is a better judge of football talent than 90% of us. From November 2019 to Olympics last year he was basically a phantom coach. I'm presuming he spent a lot of that 1.5 years poring through football videos/live games of Kiwi players overseas. He would have watched a bit of the USL. More than probably any other Kiwi. So he will know the level well, and what likes of Adams, Collier, Musa, Wynne etc offer.
So if Hay's not picking Kiwis from the USL, except Nikko Boxall (first season in USL after playing in Europe a long time) and Collier (did have 3 seasons in the MLS '18, '20 & '21) - I trust it's for good reason.