Subscribe for 33¢ / day

Dear John: I have a theory. Never have I seen so many baseball players on the disabled list as in the past several years. My theory? Too much weight lifting and not enough stretching. — Jim Quinn, via email.

Dear Jim: You must be a White Sox fan. Hardly any Cubs are on the disabled list, with just Addison Russell currently sidelined with a foot injury.

However, the White Sox DL is overpopulated, and like most teams, disproportionately with pitchers. I would further submit that there is a correlation with the two teams’ respective places in the standings.

However, getting back to the specifics of your question, as I said in my personal reply, you are on to something. The pitchers have become too strong. The Tommy John ligament is unable to withstand the forces generated by those muscles.

More specifically, young pitchers, in their teenage years, have become too strong.

Interviewed by Bob Costas for an MLB Network program in 2014, renowned orthopaedic surgeon James Andrews said the ulnar collateral ligament (UCL) in the elbow – the Tommy John ligament – is a “developmental ligament.” He went on to say that, among teenagers, because of its developmental nature, the UCL is incapable of withstanding the forces generated by a throw greater than 80 mph. Throw repeatedly above that speed, while still young, and you will wear out — and eventually tear — the UCL.

On Sunday, at the Cal Ripken 10U World Series Banquet of Champions in Schererville, keynote speaker Hal Morris — a Munster High School graduate and World Series Champion with the Reds in 1990 — echoed Andrews in his advice to the pitchers in attendance.

“Learn how to throw strikes,” he said. “Don’t worry about throwing hard.”

He went on warn against throwing breaking balls too soon, as well. The best pitch in baseball in Morris’ opinion? The straight change.

Not necessarily medical council, but the words of a career .304 hitter who went on to be a scout for the Pirates, Red Sox, and Angels and who also happens to be the son of a pediatrician.

Those who fail to heed Andrews’ and Morris’ advice may not tear their UCL as teenagers, but will arrive at the college or professional level with the structure so weakened that it is unable to withstand the higher workload of those levels, both in terms of duration and/or intensity.

Learning to control where and when the baseball is going, changing speed and location — those may be the initial keys to pitching longevity. However, the most successful pitchers at the collegiate and professional levels now throw in the 90s.

To do so, they must be strong, but to prevent UCL injury, they must be strong in the right places.

According to a Northwestern University study published in 2015 in the Annals of Biomedical Engineering, pitchers with stronger triceps muscles and wrist flexor muscles place significantly less stress on the UCL.

That same year, a study in the Journal of Orthopaedic and Sports Physical Therapy showed that those with weaker rotator cuff muscles in the shoulder are more likely to suffer elbow pain.

Consequently, Jim, it is a complicated process: performing well enough to pitch at the major league level — high speed but with pinpoint control — while at the same time avoiding the disabled list.

John Doherty is a licensed athletic trainer and physical therapist. This column reflects solely his opinion. Reach him at Follow him on Twitter @JDohertyATCPT.