well yes this will happen as the tactics you where using on 14.2.2 where successful exploiting the ME, and bugs, which are now fixed which mean you'll have to work hard to find a new one that exploits the 14.3 ME.
my suggestion is not use a downloaded tactic for now, and work out what keeps happening during the matches so you can counter them, for example, I felt my strikers kept failing to score CCC, so I dropped him back to AMC, played him as a shadow striker and it worked...most downloaded tactics that have been successful is mainly because who created them took time to work out how to win countering the match engine and bugs, for example the corner bug, that's why theres tactics that work for any team you pick.