Maybe is not about letting him go but not being able to match him?
Lots of big names appeared to be pretty knackered before the 20km to go.
Probably thanks to the earlier adverse weather
No-one wanted to sprint against Matthews, so weren't prepared to close the gap, which was easily closed if one or two teams committed, and, once again, a lack of unity meant Orica didn't take on the responsibility.
I bet Matthews had choice words for Gerrans on the bus. Again.
Virtually no action, a couple of half arsed attacks, and then they let Gasparotto ride away.