no mate, variation as in say a MC moved to DM to be a bit more defensive, or vice versa, just try not to make massive overhalls of the tactics because form will suffer badly, it may take upto 6-7 games to be getting the best out of your formation, so changing it after a couple of bad results just unsettles the players again and your back to square one.
if you look at other threads about tactics people have found the same thing as me, stick with a tactics and just tweak it a little at a time and things should start falling into place.
unlike previous versions where certain tactics seemed to be better than others and people ended up with weird and wonderfull formations, the formation itself seems less important and more emphasis is now placed upon your players becoming used to the formation and style of play.
i've landed on my feet in this incarnation of the game because ive always tried to play the same way, in a simple 4-1-3-2 formation, it started out a bit ropey for me to begin with but i stuck it through and im getting the results... well apart from during an injury crisis, but that cant be helped.
also during a match dont be scared to give the lads the hair drier treatment at half time, if they dont like it, thats the least of your worried with no wins in half a season,
take things one step at a time, work out your worst weakness and try and improve it, for example if you are leaking goals like a Kevin Keegan side sort that out first before you face the problem of your goal drough at the other end, its easier to nap a one goal win than try and get striker that are struggling to score 3 or 4 goals a game to win the match.
sorry to harp on with such a long monologue, but have you tried managing at the very foot of the footballing hierachy? at the lowest level you see the biggest difference when you make adjustments, therefore making it easier to work out what does what, this includes moral, team gelling and tactical adjustments.