out of 6 metrics, he's first in 4 at fbref too, a very close second in one, and close 4th in an other. and i'm not sure what's the methodology behind each metric. these sites usually buy their data directly from opta, and they get much more nuanced stats compared to what gets reported by sofascore or whoscored. opta might report multiple types of progressive passes, i have no idea whether datamb's and fbref's stats are directly comparable
again, just ask the guy what kind of data he used, and when he collected his data. tell him that fbref reports locatelli as 4th/5th in progressive passes among midfielders and he'll explain what i can't because i don't see what he does. dunno, locatelli might have been overtaken by guendouzi et al after he did his opta query. the guy that runs that site and twitter account seems to me like a genuine enthusiast, i wouldn't accuse him of anything before asking