Diep might be tougher than his ranking suggests. No matches in 2-3 months, so perhaps fresh following an injury. He steamrollered Fratangelo from middle of set 1.
Fratangelo's performance (losing 8 straight games to an opponent ranked hundreds of places below him) spookily similar to Oli in Israel last week. Both appeared to give up or melt down. Both were top 5 juniors in 2011, both won junior grand slams and got a fair amount of press in their home countries. It just hasn't happened for the American, less highlights than Oli for sure. Both will probably need the next 2 months to reflect and refocus - mentally I suspect as much as anything else.
Can we hope for a second all Brit all 17yo QF in the US in 2 weeks? I think it's a good bet. Fingers crossed again