Kids are hard on themselves sometimes when they lose. Thats ok that is just the natural competitive instinct that is stronger in some than others. I have seen great wrestlers that reacted either way. I think the best thing you can do is give them a big ole hug and take them for ice cream. Nothing heals a broken heart like a big cup of ice cream and hot fudge. The best wrestlers have a short memory. Try to get him to forget about it for a while and not dwell on the negative, he is a champion for being out there.