New York Yankees’ starting pitcher Luis Severino - who turned 26-years-old on Thursday - hoped to put last year’s injury-marred season behind him for good. The Yankees’ fireballer was held to a mere five starts across the regular and post-seasons during the 2019 campaign secondary to troublesome injuries involving his throwing shoulder and back. Severino, the Yankees, and the New York faithful were hoping that 2020 would be met with a clean bill of health.
Those hopes were dashed slightly on Thursday when it was reported that Severino would be shut down for the near future with right forearm discomfort. According to ESPN, Severino had been battling forearm discomfort since Game 3 of the ALCS and multiple MRI and CT scan images failed to provide a reason for his pain.
Yankees’ manager Aaron Boone told reporters that Severino mainly experiences discomfort when throwing his changeup and that a loose body was later discovered in his throwing elbow that Yankees’ doctors believe to be unrelated. (Loose body is a term used to describe free floating strands of cartilage or bone chips in a joint; they are a common finding in the elbows of baseball pitchers and sometimes cause pain and dysfunction.)
Severino’s injury is curious due to the unique circumstances in which his symptoms arise; by all accounts, the Yankee pitcher is pain free when throwing the baseball in any way that does not resemble a changeup. A changeup is usually thrown with the ball located deeper within the pitcher’s palm compared to a fast ball and most pitchers induce a greater amount of spin on the ball by over-pronating the wrist just prior to release. This over-pronation - twisting the hand down and out - ultimately causes the ball to drop and fadeaway from opposite handed batters. This is opposite of fast balls and sliders, in which pitchers supinate their wrist to cause spin and break.
There are two main muscles that function to pronate the wrist - the aptly named pronator teres near the elbow and pronator quadratus near the wrist - though the wrist flexors also assist with the movement. The wrist flexors and pronator teres attach at the medial elbow, near the UCL, which can make differentiating a ligament sprain from a tendon strain difficult without imaging. In addition to flexing and pronating the wrist, the wrist flexors provide dynamic stability for the inner elbow via their muscle contraction.
It is difficult to know what exactly is irritating Severino’s elbow as MRI and CT scans returned negative for pathology. Regardless of the anatomical structure involved, maintaining - or even improving - the strength of the wrist flexors and rotator cuff is imperative to keeping Severino’s elbow healthy. The rotator cuff muscles control the placement of the arm and reduce the amount of stress subjected to the inner elbow during the throwing motion and - as previously mentioned - the wrist flexors assist the UCL with stabilizing the elbow.
When healthy, Luis Severino has arguably been the New York Yankees’ best and most dynamic pitcher in recent memory; according to FanGraphs, Severino has accumulated 12.8 WAR in just over three years of service time. While no firm decisions have been made at this time, Severino would be the second Yankees’ starting pitcher to hit the injured list already this spring after James Paxton underwent lumbar surgery in early February.
