At what point in the match did you write this post?
I mean, I guess I would have thought that Rhyne must have done something right in the match to get a straight set win over a guy like Kudla, especially since Kudla has been playing the best tennis of his career as of late. But I'm getting a little bit of debbie downer vibe from you. What did Rhyne do well?
ETA: besides serving well
Early in the match, he ran around his backhand quite a bit to hit the forehand and didn't really try to properly construct points. Mostly just utilizing the slices (refused to hit the backhand which really irritated me). For the most part, he cruised through his service games b/c Kudla couldn't get the ball back into play (a lot of unreturnables). The first set was pretty even until 5-5 where Kudla had a loose game. In the 2nd set, Denis had a couple of early break points but Rhyne managed to hold with a combination of good plays and silly errors. Rhyne was actually less aggressive in the 2nd set. He saw that Denis was frustrated and just put the ball back into play waiting for errors. And he got plenty of donations, a lot of missed overheads. Rhyne used the dropshot quite a bit in the 2nd set which got him in trouble a couple of times (including one where he gave the break back at 4-3). But more errors from Kudla led to the final break.
In conclusion, the theme of the match is Rhyne's serve and Denis' errors.