"Not that great" doesn't equal "He's not good and can't play football"
What makes a business good is your need for the purchase. Do we need a player like Mariano? Yes. Is Mariano selfish? Yes and that's why we need him, we have a lot of players who would look for the pass more than the shot, almost every player in the squad but Bale. We needed a goalscorer whose only focus is to score and we got one for a very fair price. To be a backup. We are not buying him to be a starter. We're buying him to be a super sub and a small games player.
The only better option we have was Aspas, who is a Celta Vigo legend and would take a hard time to convince him to join a team where he will be benched. Especially considering his Liverpool forgiven season.
So, Mariano is good business for us, not great, not the best, but still good. And with a manager who can tactically and mentally utilize him, I can't see this going bad at all. So, that's my whole point.
I've seen Mariano play with Lyon, not on weekly basis but I liked the lad and I wanted to watch him as much as I could. You can put him in front of the goal and trust him, and I think we need that.