"Get your elbow up" is a fairly common piece of advice for pitchers. However, I find its use to be disturbing.
At a minimum, it reflects a misunderstand about Arm Slot.
What's worse, it may contribute to shoulder problems and even Thoracic Outlet Syndrome in baseball pitchers.
Thoracic Outlet Syndrome Elbow (TOS-Elbow)
I'm still working to isolate the exact root cause of Thoracic Outlet Syndrome Elbow (TOS-Elbow) in baseball pitchers...
Josh Beckett Thoracic Outlet Syndrome Elbow
...but it seems to be related to a combination of a Timing problem and Hyperabduction, or Flat Arm Syndrome combined with a high pitching arm side elbow, which is precisely what you see in the picture above of Josh Beckett.
Kyle Zimmer Thoracic Outlet Syndrome Elbow
Other pitchers who have high pitching arm side elbows and Thoracic Outlet Syndrome include Kyle Zimmer and Matt Harvey.
Matt Harvey Thoracic Outlet Syndrome Elbow
I believe that the image sequence below, which is from Matt Harvey's 2014 rehab, explains why he had Thoracic Outlet Syndrome.
Matt Harvey Frame 21
Matt Harvey Frame 22
Matt Harvey Frame 23
Matt Harvey Frame 24
The thing to notice is how, as he goes into foot plant and his arm comes under load, Matt Harvey's pitching arm side elbow is rising up.
Matt Harvey Frame 25
His shoulders then start to turn, and his pitching arm starts to externally rotate, while his pitching arm is at roughly 100 degrees of abduction.
So what's the alternative?
I believe the best thing to do is to follow the leads of Justin Verlander and David Price, both of whose pitching mechanics I analyze in detail in Dominant & Durable.