In the animated gif, the swing plane and the shoulder turn plane are not the same or parallel. This is one form of disconnection.
The bat is not getting the full benefit of energy created by the shoulder rotation because the arms are taking the bat in a different direction than what the shoulders are turning.
They are working against each other instead of with each other.
With a bend at the waist posture, he can make the swing plane and the shoulder turn plane the same.
Small adjustments in the tilt of your spine (inch or so) makes large adjustments in the bat.
So, to get to the various pitch heights and locations make a spinal tilt adjustment versus an arm adjustment.
With his upright posture in the .gif, he can only hit a letter high pitch and keep his swing and shoulders in the same plane.
Maybe he just made one hell of an adjustment with his arms on this swing. The others indicate he has better posture.
My question is why did he lose so much of his bend this time and not all the others.
Shoulder turn plane = \ (this is too steep but it's all my keyboard can do; change it to approx a 45 degree angle. This represents the edge of a disk that is perpendicular to the spine. The top of this, >, is closer to the proper angle of his shoulder turn plane.
Swing plane = / (again, a little too steep but not much). This represents the edge of his swing plane. Maybe the top of this, <, is closer to his swing plane.
Both should be \\.
He starts the swing off pretty good, but when those arms extend he changes the swing plane. Linear arm movement and it disconnects them from the power source. Shoulders going one way, arms another.
If he'd have tilted over more, he could have gotten to this ball and kept his arms in the same plane as the power supply.