Biwott is gunning for the NYC marathon, seven weeks from now. Ritz is gunning for Chicago, three weeks from now. Biwott could afford to go harder without fear of blowing his wad in the goal race. Ritz can't afford that luxury.
Ritz spoke not to that issue, exactly, but to the question of race-specific training--or not:
"They (the two Kenyans) broke away about 5K and I stayed in third place the rest of the way," Ritzenhein said. "I wanted to run a good, solid race, about a 4:35 or 4:40 pace. And that’s what I did. Training for the Marathon makes it so hard to respond to those fast miles, and I couldn’t. The first mile was slow. Then they took off. I ran 4:25 for the second mile, they ran 4:21. They were running fast miles and I couldn’t keep up."
What's sauce for the goose is sauce for the gander, in training terms: Biwott and the other Kenyan runner are, like Ritz, in marathon training, not half-marathon training, so the fact that Biwott was able to pull away suggests that he's simply the stronger runner right now. Still, Ritz, a month closer to his goal race, is also closer to the burnout point; one would expect some lag in his legs for that reason, too. And I wouldn't rule out the Noakes internal-governor rationale: Ritz knows that he can't afford to go balls-to-the-wall in Philly. Truly digging down into the mud would risk his goal race.
I personally think all this is moot. He hasn't yet managed to put together a truly stellar marathon--nothing that looks like his World Champs half in 2009, when he came in third and looks tough as nails doing it. If he gets a cool day in Chicago, times his training right, and doesn't go out too fast, I think he could finally run a fast one. But that is a lot of ifs.