Did anybody watch his match with Raonic at IW earlier in the year? That's possibly about as much experience FAA has had with a massive weapon for a serve.
Also, big, not massive servers:
2 losses to Stakhovsky, one due to retirement after that crazy trip from Almaty to Antwerp and a marathon 1R qualies survival. The first was USO’17 qualies.
Losses to Medvedev and Fucsovics at Toronto and Vienna last year, both in three sets.