Mhm, my horses also develop a running away problem when in a larger herd environment and/or a larger grass pasture... He's not lonely anymore, thus doesn't need human companionship and prefers not going to work.
Anyhow, here's a suggestion: Get a bit of grain in a bucket(enough to make some noise) and shake it around. This usually works, problem is, if he's with 4 other horses they are also going to want the grain.
Another, more time consuming possibility would be to get others to remove the other 4 horses from the pasture so he has no herdmates to run around with or to.
Again, in your spare time(although I know this is hard to come by) just go out into his pasture without a halter/lead rope. Give him some affection and treats, and do this several times. Then show up with his halter/lead rope and hopefully he'll be more willing to be caught.
Again, hide the lead and halter while approaching him.
Another suggestion would be to catch another horse and walk it next to him. He may think you are simply catching that one instead and be unsuspecting when you go by and you can snag him.
Also, if any of these help you catch him, don't work him. Have an enjoyable time with him - go on a trail ride, groom him, give him treats, feed him, whatever. Just make it fun. Do this a few times, and do it in between harder workouts so he doesn't only see leaving as having to go to work. (All this if he does even get worked hard.)
Maybe, once the newness of his surroundings wear off, he'll be easier to catch again. My Arab and pony can both be like this, but after they settle in they get better about it.
These are just a few things that have worked for me. Hope I helped! Oh, yea, next time don't let him win. Once they are able to escape you they get it in their head that you'll eventually give up and they'll never quit running away.
Also, get a break-away halter(with a leather headstall and a snap) and leave it on him for a while. It's safe so if he gets snagged on anything it'll just break off and he won't break his leg, neck, whatever.
Anyway, hope I helped you! :) I know how frustrating this is...