To get to the root of the problem it would be worthwhile to ask the question "what happens after he's caught that could be causing this to happen?". If a horse was previously easy to catch and that's changed, something else changed. There's a cause and effect relationship taking place there.
One thing that I've found to help tremendously in the cases of 'hard to catch' that I've had to solve is to become more aware of the first impression I make on the horse as well as the last impression I leave him with. I think that it's okay to work the horse and ask effort from him, but at the same time I'm aware that if I do that every time I catch him and then just turn him loose when I'm done then pretty soon this evasive behavior is likely to crop up. This is my solution. I make sure that when I catch my horse, I give him some time on the front end of our session to relax and get used to the idea of being with me before I start any real work. I take my sweet time in getting him ready to be ridden. I do my leading, grooming, and tacking up in such a way as to encourage myself to relax and enjoy the process. It's a little bit like meditation. That feeling will then transfer over to the horse so that by the time I'm ready to throw a leg over him we're both settled and ready to work together. The same goes for cooling a horse out and putting him away. I try to never turn a horse loose until he's completely settled. To me that means that his breathing is slow and regular, his body is relaxed, he's dry, and he shows no signs of being troubled by being with me. I want him to get into the habit of feeling good in my presence so I consider the investment of time to be well worth it. It may take awhile at first but as he adjusts to the new 'normal' of feeling good with me it will become more and more his default setting.
Finally, if a horse is inclined to be herd-bound and whirl away/take off when I remove the halter I will actually walk him all the way back to wherever the herd is and turn him loose next to the other horses. I hate to turn a horse loose far from the herd and watch him run away screaming. I think that that just encourages him to view me in a negative light and become bad to catch. On the other hand, if I take the time to walk him back to where he feels comfortable he'll begin to look at me as someone who takes him places that he wants to be.
That got a bit longer than I intended but this is a subject I struggled with a lot in the past so I've given it quite a bit of thought.