Sorry to sound so ignorant but am rather in the dark regarding this reference to pitchers. Is it velocity, arm strength, or what? The pitcher in reference is a leftie, has a 85-88 mph fastball, 2 curves, slider and circle change if that helps. Thanks

There are much more knowledgable people here than me, but I believe the reference is to the fact that the pitcher is not straining while throwing - the arm is loose and "alive" (it's not just like a wet noodle). It is not a reference to how fast one throws or what one throws, but how the arms appears to be acting while throwing. They also talk about a fastball having "life" - this I believe refers to the ball not "dying" (slowing down a lot) by the time it reaches home plate. If you see a live arm and/or a live fastball vs. anything else you'll know what they mean.

Tim Robertson