Inappropriate Role
Hulk is primarily a wing forward who can also play as a center forward when required. So, prima facie he is not a player that Chelsea require to invest in right now. While Hulk certainly can lead the line, it is not his primary strength. He is at his best when he is starting in a wider role on the right and then running at defenders.
However, Chelsea already have the likes of Willian and Schurrle filling in that role and Schurrle is also a man who can play upfront if required. So, even though Chelsea could certainly do with Hulk’s versatility, he is more of a man who is more likely to fill in as the central striker rather than lead the line every week against top class defenses.
Stats taken from squawka