I'm and not surprised by Aaron Sahlman. He has the credentials (the 14:41 last week at Woodward Park and 8:01 3k stand out for me) and had been gradually improving after injury early in the season. Plus, Aaron was the guy who pushed the pace for at least 2 miles last year at Running Lane--I believe he is largely responsible for those fast times. He took this race out again this year, but then settled back and waited. He executed the race perfectly.
As far as Leo and Lex, they said they were going to go for it, and they did. I have never seen them back down from any competition. Maybe they thought they could break away like Nico did. I do think there was a bit of miscalculation on their parts--they put in a couple of hard surges in the middle. When a runner takes a chance, there is always the risk of collapse; even the commentators mentioned it early in the race. By the way, Lex and Leo weren't the only top runners who didn't finish as was hoped. It just didn't work out for them on this day. On everyone's best day, I believe Lex and Leo are the best of a great field.
The race was exciting to watch. I see numerous super-fast times coming in track from all over the country.