Bauwman dove into the apex of the corner, squeezing off Schmid on the inside, perhaps clipping his wheel but certainly he braked and lost a little control. That pushed Schmid straight/wide, taking Vendrame and Valter wide. They were winding up to come around the outside and it just kept getting outsider into the motor pen. Schmid bounced off Vendrame and got back on track. Tonelli just sort of slimed through to third.
I thought it was closer to a penalty on Bauwman than Sean Kelly did. If it was Sagan and Cav, they'd probably both be DQd.