Hmmmmm....that doesn't seem to be what I've observed. The only time I see him have issues w/ arm strength is when he doesn't set his feet, or tries to throw on the run. He tends to use only his arm at times instead of stepping into the throw. What I'm seeing are mechanical issues due to poor footwork. There have been times when he's zipped the ball in, and it appears to me that it's happening more and more often, as his footwork appears to be improving.
Arm strength is almost entirely about throwing 20-40 yd outs and into tight windows. It has almost nothing to do w/ how far a guy can throw the ball.
I'm going to start watching even closer for "zip", because I agree w/ you that's what matters.