Ok odds have come up a bit, so now I see more value here for the argentinian so lets try this..
I dont really think this is a "great" match up to Edmund. I mean I watched him against maybe 50% fit Murray last week, and he made so stupid errors and was bad when he had to play against good returner. And Washington was faster conditions than here in Canada, and I think it suited better to Kyle's game. Yes he has a big forehand, one of the best in the business and strong serve. He likes hard courts, and only reason what I see favours him here that he has already played in US hard court swing and Diego had break after Hamburg.
Diego isn't actually imo so bad hard courter these days. Or I can say he is a good hard courter, when it comes to slower conditions like here in Canada. He was actually last year in QF here in Canadien Masters so he has some points to defend. Also he made "big" surprize beeing in QF at US Open last year which is also normally slower hard courts. So we can say he likes these conditions. Also he is now close to top-10 position, and maybe wanna "break" that end of the season. I mean he is a guy who brings every ball back, for me that is advantage against someone like Edmund.
These guys have met once and that was also in US hard courts few years back with 3 setter, so I would not be surprized to see also 3 setter this time, cause I expect lots of up and downs in this match!