Having played with Tactics of my own and other peoples over several seasons, I would say the tactic plays a pretty big part in how many chances you create and if they are good chances.
The only constant that every one has is the match engine, every other factor is down to the individual persons game.
So if someone says it is your tactics, then they are not taking into account all the variables on your game, and as it is your game, they can never hope to understand all the things going on.
For instance, in my current game, my top striker has suddenly stopped scoring, he is now 10 games with out getting a goal, is it my tactics? No, it is not. I know that because my second and third strikers are still scoring. So in this case the individual striker is having a barren spell, regardless of him having Superb morale. I wish I knew how to stop it, but it is certainly not the tactics.
BUT, if I had never been creating the chances in the first place, then this is most likely down to my tactics or me using the wrong players for the tactics.