NLF Rankings is associated with the National Federation Lacrosse (NLF) clubs. The founding clubs are Baltimore Crabs, Big 4 HHH, Laxachusetts, Leading Edge, LI Express, and Team 91 LI. It lists "affiliate clubs" as Denver Elite, Eclipse, Madlax, Prime Time, Resolute, Sweetlax, Thunder LB3, and West Coast Starz. Duenkel plays for Next Level which is not associated with NLF. Not saying that is the reason... but not saying it isn't...
I'm more excited to see Ty Xander's list on IL. There's always faults with it and it also isn't perfect, but at least he doesn't have a direct connection to clubs (as far as I know). I feel like Ty might use HS performance more in his rankings than NLF, so my guess would be Duenkel is higher on his list and I think maybe even #1.