Hmmm... tough to say without video...
personally, I know I can recognize when it was the opponents tough shot that caused me problems, and when "my shot broke down" that caused the error.
... in fact, I would say that out of 100 misses, only about 5 of them would I say "Wow? Not sure what happened there... that felt pretty good." All the rest I could attribute to a forced error or unforced error (which IMO would include hitting just deep because I tried to hit to close to the baseline, or hit it into the top of the net because I tried to cut it too close- those IMO aren't really breakdowns in the stroke as much as they are breakdowns in my over-confidence in trying for an outright winner vs a steadier, safer return.)