did they use long ball? in that case did you use "drop deeper"? if that's not the case, keep fluid the tactic and don't worry about it, they tactic will do hers
. however you can try the nxt5 which might suit you better and doesn't fall from the nxt6. like i said in the OP "i promise it will work perfectly for *almost* everyone" but at least give it a fluid try
check page 5 a guy playing inter beat juv outside 2 games in a raw 0-4 0-6.
see what went wrong and fix it
edit: i can think of many possibilities, they played close done much more, and you used low tempo, you could try remove the low tempo instructions.
might as well they played strongly on your wingers, you could switch overlapping off.
they played long ball in that case - drop deeper is a must.
you cant plug in and play, there are no 3-5 diff kind of nxt tactics, just one which dominates anything.
you need to adjust your instructions to suit the game you are playing, by seen the match report and so on.
also don't forget to train def,position if you are playing against better team and away like you just did