How was the morale of the team? Also check the team cohesion in the assistant feedback. Really helps if these are high. I think pre-season is important for this tactic. I normally play about 15 friendlies when its my first season at the club with match tactics as 50% of training to learn tactic. On general training I leave it on team cohesion on high and do not change it. Only change it if players start to complain about the amount of training. Then when the season starts I move to teamwork. Most clubs I manage I get to "the players would die for one another" which I think really helps the tactic.
If its a normal pre-season with the tactic already learnt I use pre-season to get fitness up and learn tactic the amount lost in the bars during player holidays and go straight to teamwork. I think this does help.
Also check the key passes for your throw in guy, it should be way above everyone else, if not some element of the throw routine is not working out, could be the thrower i.e. he doesn't have the necessary stats, or the shooter. I find some players just let fly more than others, you want the regista to have the long shots and take as many as he can, he wont score all the time but the ball will fall to the strikers or CM in the box for tap in. Even without the throw in routine the tactic works genuinely really well, as can be seen by my promotion in Indonesia and then subsequent title win, where I had none of the necessary stats and PPM avaliable to me.