Lothar of the hill people

Was a bad Saturday Night live sketch in the early 90's.
I felt like Lothar today.
20mi with over 1000ft of climb and 1000ft of decent. 2x times the cowtown course.
I had to stop at 20. Had planned to go for 22 but I knew/thought I was gonna have problems from the time I woke up. I just didn't have the legs today.
I started to feel ham cramps coming on at about mile 17. So I pulled the pace back and shut down the timer and walked as soon as I heard my iPhone lady tell me I was at mile 20.
Today I was 3:07 over the tougher 20mi course. But I can't just blame the hills. In looking at my splits, I was 10 to 15 sec slower each mile right out of the gate.
Why?
Not sure. It could be that I did more work yesterday on the bike than I thought I had at the time. I also rode at 3pm instead of 6am yesterday. So 9 hrs less rest.
It could be cumulative fatigue. Long run Thursday, wod Friday, ride and wod Saturday before today's run.
It could so be right between my ears.
2 weeks ago I hit a big pr for 20mi. It would be natural to have a let down in intensity.
In any event, the hay is in the barn!
Nap time!