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Will the Corey Kluber we saw in May ever return?

Corey Kluber is expected to return this season, but will he be the same pitcher we saw in May?

MLB: Washington Nationals at New York Yankees Andy Marlin-USA TODAY Sports

When the Yankees signed Corey Kluber to a one-year $11 million dollar contract this past off-season, everyone agreed it was a calculated risk. “How big of a risk?” was the question that had a wide spectrum of answers.

We’ve all been watching, so there’s no need for a deep statistical breakdown of his 2021 performance, but if you happen to be joining us late, here’s the short version: Kluber had a great May after a not very good April. (This is an important point that we’ll return to in a minute.) Then, on May 25th, he was removed from a start after only three innings due to what we later learned was a strain of the subscapularis in his throwing shoulder. Virtually every report has him missing a minimum of eight weeks.

Now we’re presented with a different question: What is the likelihood Corey Kluber pitches substantive innings for the Yankees again? Obviously, it’s a complex issue as there are limitless variables at play. Anyone who tells you they know for certain what to expect from Kluber ongoing is just guessing. What we can do today, is focus on what we do know.

There are not many indisputable truisms in the fields of injury prevention and injury rehabilitation, but what we know for sure is this: The best predictor of future injuries is the number of past injuries. Nothing is set in stone, but every injury increases the chances of another one happening. There are a few reasons for this:

(Once again, with a nod to Russell Carleton of Baseball Prospectus…)

Warning: Gory Biomechanical Details Ahead!

When we’re injured, our central nervous system changes our movement patterns to avoid pain, whether we’re aware of it or not. For example, if you sprain your ankle, you may not consciously say “I’m going to invert my ankle 5 degrees upon heel strike when walking because 1 degree of eversion hurts”, but your body will do that for you to avoid pain – it’s a subconscious defense mechanism. More often than not, the “new” movement pattern and function stay long after the pain is gone because we’re used to it and it’s become normal. In the case of the sprained ankle, if the ankle is moving differently, the knee will move differently too (they’re attached by the same bone) and that increases the chance of altered movement – and ultimately injury at the knee.

Another reason injuries have a tendency to lead to further injuries is the typically overlooked neuro-muscular aspect. We have nerves all over our body that send messages to our brain about our body position, then the brain sends messages to every muscle to move us accordingly. That is a highly complex process. When there’s an injury, it’s not just muscle and tissue that are injured, the nerves in the injured area are affected as well. As a result, they tend to send less accurate information in a less efficient manner to our central nervous system, which affects how our central nervous system responds. (It’s not unlike a computer – a computer only responds to its input, and poor input results in poor output.) This has a deleterious effect on our movement, which again increases the chance of injury not just at the injured site, but to connected joints and muscles as well, as their movement will be subsequently altered.

The above is a general, overly simplified synopsis. Unfortunately, with regards to today’s conversation, we’re discussing the shoulder, which is a highly complex area – perhaps the most complex in the body. On a base level, it’s a ball and socket joint, but as it was once described to me it’s more like an orange in a shot glass, and the orange doesn’t want to stay in the shot glass.

To make matters worse, the subscapularis is one of the muscles that’s largely responsible for keeping the ball in the socket. Don’t be distracted if you do a Google search and see that the subscapularis can internally rotate the arm – it “can” in an assisting manner, but that’s not its responsibility. The moving of the arm is largely up to the big muscles we see in the mirror (OK, maybe you and I can’t see those muscles in the mirror, but you can see them on Corey Kluber.) The subscapularis’ primary responsibility is to work in conjunction with the other rotator cuff muscles to stabilize the shoulder during use – i.e., keep the orange in the shot glass.

Now let’s review: One muscle, of a larger group of muscles, that works in conjunction with each other, that requires a very high degree of timing and coordination, and relies on efficient neural input has been damaged – not to be confused with the muscle in the shoulder that was previously damaged. And if this muscle doesn’t function properly, there will be a lack of stabilization in the shoulder joint leading to excessive movement and strain on the muscles, ligaments, and tendons in the area, which of course leads to pain and injury.

This is a good time to remind everyone that if we were discussing you and me, as long as there’s no pain, you and I could get on just fine with sub-optimal neural function. We could use our phones, type on our laptops, play with the kids and even fling the ball around the yard with the dog, just fine. We’re discussing someone whose job is to hurl an object accurately in a powerful manner thousands of times over the course of a few months.

Now let’s circle back to my earlier point about Kluber’s April ineffectiveness compared to his May effectiveness: Let’s play glass half full and assume the muscle tissue heals and everything is pain-free after eight weeks. That doesn’t mean the coordination of the shoulder and arm are optimal, which needless to say, is pretty darn important when aiming a ball at a target. This would explain the disparities in his early-season performance – his coordination of the arm just wasn’t very good initially, and he didn’t have a great command of his pitches. With more practice and more reps as the season progressed into May, the coordination and command improved, leading to better results. (Ironically, if there was a lack of stabilization, more reps may have led to the most recent injury.)

What is the likelihood Corey Kluber pitches substantive innings for the Yankees again?

Again, no one has a Magic 8 Ball, but if I were a betting man, I’d bet on not likely. Assuming he’s pain-free and back on the mound in two months, that doesn’t mean the command is going to be there initially. As discussed, when and if the command returns and the number of pitches rises, the chance for another potential injury increases. All of this will be taking place in August and September, nearing not only the season’s end but the end of Kluber’s contract with the Yankees as well.

Is it possible to see a big game or two in a big spot down the stretch or in the postseason from him? Of course, but I’d say the odds are against Kluber returning to his May form, that of a strong number-two starter. When playing Blackjack, sometimes you hit when you’re sitting on 19 and the dealer gives you a 2. That doesn’t mean that’s a bet you want to make.