Our 'bot lost its trailer after a hard hit from another. Worse, an alliance mate drove away from the trailer as soon as autonomous started. The killer: this was in the same match.
The other team probably had the pin miss the trailer tongue completely, the only scenario that seems likely. Our pin was installed by a pretty sharp young man, our programmer. It was also the first time he had done it (all the kids were having a try at different responsibilities, as we were so far down in the rankings). Here's what's weird: he said the pin was still in the hitch through both upper and lower holes. He said he had put the clip around the pin. I didn't see it myself, so can't verify or deny. It seems unlikely, but at the same time, I don't see how the trailer could have made it partially through the match if it hadn't been connected to begin with.
I don't know if a team can supply their own pin to be sure it's good. Pin installations weren't being checked by staff, as far as I can tell. (Two trailers off in the same match? No double-checking there.) But, I would strongly recommend you do what you can to prevent separation. This is a terrible way to kill a match. The trailer sits there like a dead duck, getting dumped on. This kind of thing should simply not happen.
mt