Elbow above shoulder at foot strike is a bad bad thing.
But it isn’t the only factor in arm issues. Lack of continuity in posture can have just as drastic and affect. What I mean by lack of continuity is that the angle between waistline and chest changes dramatically. Here’s a look at Tim Lincecum, who has good postural efficiency.
See how little his posture changes. He starts with his body leaning towards first base, and continues to do so throughout his delivery and into release. The angle is relatively the same the whole time.
Tim Lincecum is incredibly efficient mechanically, so what about those who aren’t. What happens is the body pulls off right before release in order to put maximum effort into the ball. If you drastically change your body tilt right before release, physics says all of the force will jump into the arm. Jumping force is what causes injury, its why you’re more likely to pull a hamstring while sprinting then doing leg curls. Here’s an example. Notice how he starts on the right side and then pulls off a lot to the left. So much so that his head pulls off as well. Johnson, in comparison, changes very little, and a result his head stays put. You can see the stress difference in the arms.
Maximum effort is good so the posture at release is deemed good as well. The problem therefore is that our posture previous at release was most likely too far inward. Notice how even as Lincecum is leg lifting, his body is leaning towards first. That’s called presetting your posture. That way his body can still put all of its force behind the ball without having to jerk and put stress on the elbow.