What are some characteristics of a “loose” arm?
for me personally its when i throw full velocity and nothing hurts
100% velocity without discomfort.
Is someone is telling you that you don’t warm up long enough?
For me, “loose arm” tranlates to “strong and flexible”—being able to go the distance without fatigue. I was a finesse pitcher, not much in the way of speed but with a good arsenal of offspeed pitches and breaking stuff, the control and command to go with them, and the ability to mix up my pitches and keep the hitters off balance, inning after inning. I was a sidearmer with a consistent release point, I used the crossfire extensively, and I was in the habit of throwing strikes—or what looked like strikes, much to the discomfiture of batters who could never set themselves fo any particular pitch. And go the distance I did—as a starter I could go nine innings, and I could relieve between starts with no trouble at all. Nor did I need a lot of time to warm up before a game.
They say “you never forget your first”, and I will never forget my first appearance in a game. I had been asked if I could pitch the last three innings of one particular game because the starter had to leave at the end of the sixth to go to work, and so I warmed up and came in at the start of the seventh. I pitched three scoreless innings—in one of them I walked a batter who was promptly erased in a 6-4-3 double play—and struck out six and didn’t give up a hit. Also, in my one time at bat I walked and scored on the next batter’s triple. We won, 5-2, and the manager of the team asked me if I would like to play regularly with them. With a lot of free weekends at my disposal, I agreed, and thus began more than twenty years of just plain fun pitching, with no problems, no sore arm or sore anything else, and as the years went by I got even tougher on the mound. 8)
I’d characterize it as a fluid, effortless motion.