Perez is still drive like mid-pack team driver. He is just not up there yet. Top level drivers like ALO, HAM, RAI, VET, and I'll throw in BUT and WEB, they all can deliver here and there with decent or mediocre cars. MAS is a bit better but more because of his confidence and mentality.
But or PER, he's just doesn't have the race craft and skill set like the top drivers I mentioned, at the moment.