High bar judges tend to score gymnast very low on their execution (it probably has the lowest execution score averages across any apparatus, even lower than pommel horse). Most men, even Uchimura, struggle to hit their handstand positions (pirouettes to hand stands etc.). You will almost never see an execution score of 8.8 and above... the highest execution score on high bar yesterday belonged to Belyavskiy - 8.733. For future reference:
Uchimura had a start value of 17.1, that's 0.6 ahead of Verniaiev; Uchimura's execution score was 0.4 higher than Verniaiev; Uchimura stuck his dismount, Verniaiev didn't (for parallel bars too, which he normally does... all those precious tenths) and probably explains at least 0.3 of the 0.4 difference in execution scores. It was painfully close.