Why Do Sprinters Use A Straighter Arm Pull?

Noa Markou just asked us a great question on Instagram:

I read your article (www.feelforthewater.com/2012/08/bent-it-like-becky.html) and would greatly value your opinion on the following. It states that an elbow bend of around 110° offers the most propulsion. If that is the case, why do sprinters who need maximum propulsion catch with straight arms? Tha…