Pity. But 53% first serves in combined with 51% of points won when that first serve was in (so essentially the first serve yielding just over a quarter of its possible points ) is no basis for anything very much. 9 DFs ( with 2 aces ) didn't help.
Sounds like the effort of the previous round took too much out of him. Stats were better in the earlier match - 60.7% and 72.2%, so 43.8% on first serve.
From the man himself
Neil Pauffley @NeilPauffley 12m
Went down in the quarters 6-2 6-4. Had nothing left in my legs to give. Physically drained from my previous match. Two tournies to go