When he was 3 he told us he was seeing double. He didn't really know how to communicate it, but he didn't like it.
That probably saved his vision.
At this age, he still knows not to mess about with that type of lie. I'm not saying he is an angel, just one of those kids who are rule sticklers. It probably runs in the family. ;>
I'm confident now that it is using new muscles.
He doesn't like getting on top of the ball and even if I get him to start that way, he'll turn it into a side arm.
For me, the really positive aspect of this has been in breaking down the game of catch. To keep from stressing his arm, I took a bucket of balls and just had him catch - no throw back.
He used to like to catch at the waist, with his glove palm up. I'd never been able to break that habit. So there I had him, throwing dart after dart at his upright glove. "Daddy, I can't do this." Snag. "It doesn't feel right." Snag.
After ten catches, he stops complaining and now the bucket of balls is one of his requirements for a practice. He is also more inclined for the proper form for fly balls.
I smacked him good on the head one time. We had to start with the waist catching and rebuild his confidence. But he is back to wanting the buckets.
We also have him throw a bucket of them back. By taking out the frustration of missing, both of our attitudes are better. If a ball goes behind me, well another is on the way. I don't have to shag it for some time.