As I was working on Efficient Not Strong, I realized that something was missing from Matt Carpenter's swing.

That something is what I have previously called a Resisting Movement.

And realized I should just call Resistance.

Matt Carpenter 2018

Put simply, Resistance is Resistance to Rotation.

Matt Carpenter 2018

Resistance is what helps keep the shoulders closed and creates Separation.

Without Resistance, hitters are prone to developing Leaky Hands.

This 2018 clip of Matt Carpenter shows why he got into trouble and didn't get going until August.

Matt Carpenter 2018

While this was a home run, the problem is there's little to no evidence of Loading Up, Loading Around, a Runing Start, Overlap, Scap Loading, or anything similar in the clip above. Instead, Matt Carpenter's hands just stay back and then go forward. That's not necessarily bad, but there's nothing to keep them from leaking forward.

I'd suggest that's what lead to Matt Carpenter's slow start in 2018 and miserable 2019.