So his suggestion on causality was that the reason teams who score more cross less is because the teams who score more tend to be in front and would therefore be attacking less. The teams that score less would be attacking more often because they're behind and would therefore cross more.Scara, he was only talking about crosses, so I'm not sure it is fair to mention "other forms of attack" nor "defensive problems caused". Perhaps you could expand your comment, I don't really follow your point.
For that to make sense, it would have to be a measurable effect across all forms of attacking, but it's not. Teams that score more play more through balls and cut backs than those who don't.