I agree with the "lessons" theory.
Last summer, I was regularly shooting in the low 90's, and had a 21 cap. I took a block of lessons which fixed a lot of dumb things I was doing almost immediately, and within 2 weeks was shooting closer to 85 (and carded 2 rounds into system of 85). During this time, we had a tournament, and I shot 83, so net 62.
I also saw a guy in my flight at a different event with a 16 shoot a 77. Everyone can have a good day sometimes. (she shot 90 the next day, though!)
It all evens out in the end, you have to hope.
(I think the real lesson of my store is that I should go back to taking lessons!)