Strikers who aren't natural at the shadow striker role will obviously perform at 70% of their actual ability, which is why it's important from the off to either sign natural shadow strikers or retrain strikers in the shadow striker role. This can take a few weeks but if the player is extremely good it will definitely be worth it. Head over to your individual training and set your striker to "shadow striker".
If your striker has no rating for a shadow striker, obviously you need to decide if to train him into a shadow striker, this can take longer but if the player is extremely good, it's worth it.
Both the wing backs are extremely important positions in this tactic, they contribut greatly to attacking and defensive duties, they get tired very quick so having sufficient back ups is vital.
This tactic on FM17 took us from National South to the Premier League with Whitehawk consecutively and we also finished 2nd in our 1st season in the Premier League.