He's been a very selfless team-mate in the past, and this season. Has only had two race days since Itzulia, and been in the break three times this race. He's probably just knackered.
The fact is Simmons dropped Van den Broucke like a stone on the second last ascent of the final climb. Then when called back he lost time pulling on the flat to Van Den Broucke. And Simmons is a better rouleur than Van den Broucke.