I saw some of Sock's match against Johnson and they were both awful. When the draw came out, I wondered how he would fare against a player like Cipolla who makes you rally and I guess I have my answer now.
Harrison has his faults but he's a far better player than Sock.
The thing is that someone like Sock has the game to prevent rallies from happening: if he served and returned really well (Cipo's serve can definitely be obliterated), he could have won.
Harrison and Sock are not at all comparable in terms of game.