I don't think he would be a bad signing in conjunction with someone like Jovetic. And he's certainly a step up from every other striker we've had in the past few seasons, aside from one.
It'll be good to have someone who actually had made it as a top footballer and knows what it takes at the highest level. As Qs said some time ago, the mentality at this club is to finish fourth because they don't know any better, bringing in a World cup and Champions league winner will help change that dynamic.
I also don't think his own decline explains his drop in form. He's been injured and asked to play second fiddle to Messi, which is bound to have a knock on effect. For his own sake, he's got to get out of Barcelona.