Training doesn't tell you very much about match performance. With your reasoning, every manager would be always right, and you'd not have to fire managers ever. If this would be Mourinho's favourite 11, it wouldn't be the first time that he'd play such a strange formation.
He is just desperate, has no clue what he can do to make things better, and just throws everything over. I wouldn't be surprised if we win anyhow, because Swansea is utterly poor. But if, he'd play the same team next time, and that would be a shame. Same thing happened with this Rojo Blind central defense, it worked once, and he thinks he found the new holy grail - for a week.