I think a bigger issue for Querrey is the fact that (1) this is only his 3rd ever 4R match in his 38th Slam appearance (he lost his first 2) and (2) the fact that he had a somewhat mammoth 1R match, which are factors that - when combined with his effort vs. the Joker - add up to maybe this being one rung too high on the ladder for him to climb. But beating a big name in and of itself imo doesn't necessarily automatically lead to a next match letdown. It can equally send someone into a mindset that sends them "over the top" where they're infused with the belief that since they beat the best, they can beat anybody. To me that's what happened to Lisicki during her final run in '13 after she beat Serena. Of course being in the Final snapped her out of her 'high' and we all know what happened next. But she had no letdown after beating Serena, undoubtedly the biggest win of her career.