No, you are even dumber now.
1. Nowhere did I say that I was confident or overconfident in marathoners ability to move down. Nor did I say that they would have a good kick. A kick isn't even necessary to be successful. All I did was show examples that it is easily possible that some of these marathoners could move down and be successful. I even mentioned specific names of people who have been successful at both distances. So you're wrong. We DO know. Or are you going to tell me that Geb and Wanjiru never ran a 10k? It's not unrealized potential. It has actually happened.
2. I don't know what your obsession is with the word "confident". Nowhere in my post did I say that "ALL" of the change is because of more opportunities on the road. Nor did I say that self selection was impossible. You're creating arguments that don't exist. All I did was provide a rational and easily possible explanation for the move to the roads. It makes sense. You know it does. Don't be stupid.
3. There's your weird obsession with "confident" again. You're displaying your dumbness here again. There very thing you accuse me of not doing, I in fact did do in the very paragraph you mentioned. I listed explanations that could happen independently or that could come into play at the same time. Please tell me what other possibilities would explain the data we have? You're either not fast enough or dumb at racing tactics or both. There are no other other options unless you want to include indirect things like bribery, etc.