19 games vs 2 games.
Not a fair comparison.
12 vs 9 is fair.
You can't just pick A and B randomly and say because A has happened without B then we don't need B to achieve C. There are other factors as well.
Opposition. Their form. Other players form. Do we dominate in terms of possesion more or less without Carew than with him. And prove that what you come up with is related to Carews absence and nothing else. And even if you do prove it has been true, you also have to prove it will continue to be true in the future.
By exactly the same logic as you I can say that he would have been top scorer for us had he not been injured. I am pretty sure he has a better goal per minute played ratio than Gabby. At least in the league, but I can't be bothered to look it up.
I'm sure there is no coincidence that football clubs are being managed by experienced former players and not by mathematicians.
As I said with regards to opposition...
We lost to Boro, Stoke and Newcastle with Carew.
We got 8 points from Everton away, Arsenal home/away and Man Utd without him.
So opposition critique does Carew no favours.
Possession is irrelevant. The object of the game is to score more than the opposition, not to keep the ball more.
I think it's no coincidence that all managers use pro zone, statistics are very important in football.