Pep played him initially at RW then CF. On the wing he can lack pace, as CF he can finish.
Aguero going to Barca left Jesus or Torres at City as the strikers, Jesus, pep converts to RW and he appears competitive to Mahrez. That appears to leave CF for Torres. I wonder if the negotiation for Harry Kane unsettled Torres? Speculation on my part.
But the choice of a return to Spain, play for Barca, probably regular starting place, seems attractive to him.
What makes him the better player? I think if he stays with Pep longer that would develop him more. Though the cost goes up.
The question though is how much would you ask for him if Barca was selling? That is the figure, or player swap, that City would take.