You would think that running a FCP at a -5 would be counterintuitive and in real life it probably would be, but here it can work and can work effectively in the right situations. If I were your friend, I'd be a little careful about running defenses at extreme settings as they tend to produce extreme results (at least moreso than balanced settings, which tends to make sense if you think about it), but if his opponent doesn't shoot any threes, a -5 could be very effective against his team.