Not really that surprising. Rosberg, Vettel, Verstappen were always closer to him than Perez is to Verstappen now such that the lead would change regularly after initial pitstops. The gulf between Red Bull and the rest of the field and between VER and PER is just that big.
That's quite an impressive feat; although how was Senna's car compared to the field in his day? I really need to go back and watch some of the classic seasons.