I’d put Sauber/Alfa, Haas, and Williams as clear backmarkers.
Renault/Racing Point (Aston/Force India)/McLaren mid-field
Toro Rosso/Ferrari mid-field-adjacent (sometimes better/often worse)
That is how I’d rank them by 2020.
BTW, Force India was 4th or 5th in the WCC in 2014/15/16/17 IIRC. They fell back in 18/19, but…