If I had to hazard a guess as to why Shane doesn't do well in this format, I would say:
1) For a guy that hits balls non-stop and always practices, he's clearly a guy that needs to hit many balls to get warmed up and to get into the zone. I think that I heard that no players were even allowed to hit a ball on the table before the match.
2) Shane uses a very long bridge, which really isn't as easy to control as a shorter bridge and a more compact stroke. To me, this relates to him missing quite a few routine shots because he had no chance to warm up his big stroke. Many players have a separate more compact stroke that they use to sintch balls when they need to under pressure.
3) Shane shines in long gambling matches with winner break. While Shane seemed to do okay with the cut break, his typical huge breaking advantage does not come into play at all in these matches with alternate break.
4) In a recent match of Shane's before the MC where Darren was commentating, Darren pointed out that early in the match it is a known fact that Shane will out of the blue, miss a routine shot. But that Shane usually won't make that mistake again for the rest of the match. Well, in these short races, one miss of an easy shot may cost you the match.
5) I really don't think that him liking a team environment or not came into play at all for his poor play. It's still him alone at the table executing his shots. Although it is possible that the added pressure of so many others counting on his every move came into play, including the extra pressure of the screaming fans and the environment.
In conclusion, no warming up, long stroke that is harder to control, known to miss routine shots until warmed up, no breaking advantage, and extra pressure is all it takes for Shane not to shine in this format.