Your second formation is useful when you're playing a team that is parking the bus and your back 3 is more athletic than the players they're marking. 3w defense in a man-to-man when you have an advantage in physical and mental stats + 2 DMC to break up the longball over the top (neutralizing the counter-attack game). normal mental too, so not to help feed the opponents counters.
I setup that way when I use this tactic when facing an opponent that likes to dig in like its trench warfare.