I wouldn't say 3 tiers below NHL level
Well there is little need to speculate. If we agree Chmielewski was the best Polish player in recent memory (pretty obvious call to make), he, at his peak, was a complimentary scorer in the Czech league. Seems pretty fair to separate tiers into:
1) NHL
2) Impact player in the European top leagues (SHL, KHL, NLA)/Star player in the 2nd tier league (Liiga, DEL, Extraliga) > Mantas Armalis
3) Solid roster player in the top leagues/Impact player in the 2nd tier league/Star player at the 3rd tier league (Austria, Slovakia) > Liam Kirk, Vilmos Gallo, Igor Merezhko, Robert Rooba
4) Fringe player in the top league/Solid roster player in the 2nd tier league/Impact player in the 3rd tier league > Aron Chmielewski, Nerijus Ališauskas
I think that's a fair evaluation with a clear separation in quality between those players. Many of them have showcased in their careers how big are the gaps between these levels, namely Gallo moving between SHL and Liiga and Rooba moving from Liiga to KHL. Same applies to the levels deeper down, like Wronka's persistent attempts to continue his career outside of Poland or numerous Poles trying to carve out any kind of role in the Czech and Slovak leagues.
Regarding the players who could
easily play in the AHL, I'm really interested to know who those are. Because players who could easily play in the AHL could also easily play in the Czech league and we see the best Poles failing to make it there fairly consistently.