Juve were in shambles before Conte came how'd you expect Marchisio to perform as WC player when the entire team playing like shit and he was one of the youngster in the team. Though during that dark period he scored some beautiful goals one of them against Inter.
During Allegri era he was WC for 2 seasons but injury cut his career short. If not for that injury he would've had more WC seasons under Allegri and retire here.
Vidal, Pirlo, Pogba looked stronger because they have specialty in their game. Vidal with tackles and goalscoring instinct, Pirlo with passing, vision, and set pieces, Pogba with strong physique, dribble and technique. These kind of players tend to be rated higher but actually they have their own weaknesses. While Marchisio was solid 8 in all aspects, he did't steal spotlight but he was the one who made the team ticking