I would put him on a prong collar and leash and have someone bounce the ball and pop the leash if he even looks at! Tell him no and praise him when he ignores it. You need a good leash I prefer leather and a prong collar that fits properly. I would suggest a 14" small prong collar and if you need to add extra links add them but the bigger the links in the collar the less effective it is. I have ball crazy dogs and we start this when they are puppies. They just need to understand to control that impulse.
Good luck. Balls are my pup's weak point. No ball is safe especially basketballs. He pops a good one in 10 seconds max! Finally got him trained to leave it. But I can see his poor brain about to burst cause he wants that ball sooooooo bad!! Now we are working on him listening to others who tell him to "leave it"
i would get a better kennel at the very least. ive noticed that once a dog knows he can escape he will do so more often. your dog escaped to get a ball and now that he knows how to do it he might escape each time he sees something that he wants. a more secure kennel might be a good idea.
What kind of exercise and how much does he get each day? Do you play fetch with him? If not maybe ou should start. It is great exercise for the dog. You do need to teach hm to leave it but if he is that crazy for the bal I would incorperate playtime with a ba for him each day.