Here is an episode of Sports Science. It talks about how much time a QB needs to throw the ball, and how quick the DE needs to get to the QB. It shows the effects of the LT making the DE adjust and Arm Length is (1) 'tool' they can use to slow the DE and make him take a wider arc to the QB. Proper technique is always the most important feature in the LT.
Sports Science: Ben Roethlisberger