Just to be clear, the Segunda Division - Liga Premier is indeed the third division of Mexican football, while the fourth division is the Segunda Division - Liga de Nuevos Talentos. There is also a division below that Tercera Division.
Mexico is a real football country and Liga MX has higher salaries on average than Ligue 1 (PSG aside). It is in the top 10 or maybe 8 worldwide nowdays.
The Liga Premier is very much structured like the USL with all the 18 reserve teams of the Liga MX clubs, a few Ascenso reserve teams and a few independents. Murcielagos 2 group includes the reserves of Tigres, Monterrey, Santos, and Tijuana among others. Many teams in Liga MX source their youngsters directly from this league nowdays.
Jerrel Britto will play along side Devaughn Elliott (ex W Connection) who is coming off of a great season in El Salvador with Pasaquina and who has a guaranteed 2 year contract to be part of the Ascenso team starting in June (he has to wait until then due to all foreign spots being taken until then, otherwise Jomal Williams was already in negotiation to take the spot on Murcielagos 2 with Britto. Only two foreigners allowed on that team). The Ascenso team will let go two of their foreigners in June leaving an open spot for Britto if he proves himself but he could also impress the likes of Tigres, Monterrey, etc...
In the case of Murcielagos 2, they are actually the original Murcielagos team and play in a different city (Guamuchil) compared to the Ascenso team playing in Los Mochis, a franchise that was acquired by the same ownership only last summer from Irapuato. That means Murcielagos 2 could actually achieve promotion to Ascenso MX and would then operate under a different name.
Now let's make it clear that Ascenso MX is a lot better than the NASL and it would be safe to assume the Segunda Division - Liga Premier is probably better than USL. Britto will play with two former Mexico U17 World Cup champs who are now about his age.
Salaries in Ascenso can average $10,000/month with top players making $20,000/month or more. Many decent players in Ascenso MX could easily play in MLS and make a difference. You could look up Yohance's teammate Rodrigo Pastorini track record in Uruguay first division and Romania. Or Nicolas Vigneri, 15 caps with Uruguay. Those type of players do not play in NASL.
In Ascenso MX the level is good. A top Ascenso team in MX would probably make the playoffs in MLS. That's why players like Quintero of Panama play in Ascenso. Kudos to Yohance for establishing himself there.