aw, Zeke sounds like he's doing really well! I've heard that most dogs do go through this, it's natural, especially for dogs who go to the dog park and play with other dogs often. Our flyball trainer made me take Gonzo to our dog park and practice in the field right next to it. It isn't fair at all to make your dog stay and ignore other dogs, and it totally could make them aggressive toward dogs. Just having that distraction there is enough. I would just practice recall with a long line for 10 minutes or so, then play ball for a while and leave. If you can, get some one else to hold on to Zeke, while you run across the field holding a tug toy, then have them release him when you yell Go. When he comes to you, tug and praise and give him treats if you want. Start at short distances, then increase the distance.

Almost everyone I've met says that running away from your dog and yelling (like a crazy person) is one of the best ways to get a good recall. Practice recall whenever you can during flyball training, and try running him in practice with this method. What I do with Gonzo, is send him over the jumps, and right after he gets the ball and he's coming back, I yell "Gonzyy!" and run the other way, holding his tug out.. he races back, grabs his tug and gets praise. It probably looks really dumb, but it works. Of course, he also still has passing issues (unless he's starting) so I'm not the best advice on this just more hard training and letting him get used to Flyball will help him a lot.