I actually really liked this, managed to get to wave 5 before getting beaten to death. I think the only problem with the catch and throw mechanic is that you have to click on the specific ball you want, which is a lot more difficult than it is satisfying. A really good foundation and concept though. If you wanted to take this further, I would make it so that to catch a ball, you have to left click just before a ball hits you, and then it will automatically pick up the closest ball to you, then give you an indicator to show where you are aiming. If you did this I would also put a small window on how often you can pick up a new ball after throwing one to stop people just standing in the middle and spamming left click.
One last thing, put a screenshot or 2 on this page, people are a lot more likely to download and play it that way