I have got my own "theory" with that since lately.
I am a visual thinker and like concepts to be, well, visualized... - I take anything tangible, graphs, 3 D models, experiments.
Once things become 'abstract' (not less real, just abstract, ), I am lost, don't give me the 4th Dimension and space-time, I will have nightmares trying to figure it out.
The best example for how "good" at maths I was is this:
In grammar school we were taking a maths test and we were asked to write down one of the bog standard formulas and explain it.
Well, I had forgotten the darned formula, but could remember everything else about it and wrote it down in my descriptive visual way. I described a mathematical formula with a page of text by remembering what I had understood of its function during class.
My maths teacher said he had never seen anything like it and gave me 50% of the marks for it, .
He was also the one that bumped into me a year after we left school at the train station and asked whether I was studying maths now - being the stupid literal ass I am, I stuttered that I wasn't and he must have forgotten how horrible I used to be at maths, He just cracked up and said, no, he hadn't ...