Jittery Joe Berry was a fidgety righthander with a herky-jerky delivery who spent 18 years in the minors before debuting with the Cubs as a 37-year-old rookie. Jittery Joe didn't do much for the Cubs (2 innings pitched, gave up 7 hits), so they traded him to the A's, where he had two good seasons during the war years of 1944 and 1945 (as a 39 and 40 year old).

His A's teammate Lum Harris described him this way:

"Jittery was a high-strung, funny boy from Little Rock. He’d never get on the scales to see how much he weighed. He was a very thin fellow who weighed only about 135 pounds. During a game he’d take out after a baserunner; he’d run from the mound right toward him. I remember one day Lou Boudreau was on third base, about ten feet off the bag, and Joe just left the mound and ran directly at him. Evidently Boudreau kind of froze, and he had to dive to get back to the bag safely. But really, his move to the bases was no different from that of anyone else. He got his nickname from his temperament, not his pickoff move. I remember another incident involving Berry. We were playing an exhibition game in Atlantic City. The bases were loaded with the score tied in the last inning, and Jittery was on the mound. He went into a big, long windup and suddenly a gust of ocean wind came up and blew him right off the mound, causing him to balk and lose the game!"