IMHO Grosjean and Stroll have exceeded expectations... Max hasn't lost his cool... Seb hasn't thrown one away... My clear underperformed has to be Lewis... He's winless to date. Don't think anyone would have predicted that during winter testing.
Grojean hasn't crashed into anyone, yet. Ham has not had to replay his best fans in the world speech.
The fact that Lec won two races, and then donned a banana costume confirmed he's the best driver of 2020 so far.