Baseball is way harder on an arm. Throwing a football can be compared to throwing a fastball, but pitchers need to throw sliders and curves and splitters which put huge strain on the arm especially the elbow. I have been pitching competitively for 50 years and was a sports producer for MLB. Almost every pitcher gets Tommy John surgery these days. They all tear up their arms. Much rarer for a QB to tear one. Can't remember one ever doing it on just a throw. Purdy did it because his arm was hit and bent while he was throwing.
