I think Morata can turn into a strong goalscorer, I'm just talking about a worst case scenario which helps me feel better about paying a big fee. It helps that his biggest weakness as a player, his indecisiveness in the box, is something that Wenger has helped loads of players improve.
And I don't think Morata needs to be a 30 goal scorer to be worth £57m. Look at the market for strikers. Take your pick of anybody 26 years old or younger to play the #9 (a list of forwards in that age range is here). There are so few players who can do what we need at that position, and it's probably the most important one when it comes to winning domestic leagues. You have to pay a big premium for a proper 9, just the way it is.
