The option becomes an obligation if:
-he scores 15 EPL goals or
-he scores 5 EL goals while they win the competition or, and this is what we are still hoping for
-he scores 1 EPL goal (check) while they finish 3rd on the table.
Tottenham is doing us a huge favor lately by keeping Chelsea close to them and now even surrendering the 3rd place to them, so we might actually succeed in getting rid of him. But keep in mind, these conditions arent officially confirmed by either us or Chelsea, its only what the media "leaked" at the time of the transfer. The official press release from Juve only states that Chelsea has an option to either extend the loan for another 12 months for another 18M euros, or buy him permanently for 36M euros payable in 2 financial years. So even if they finish 3rd, we might see him back
I hope it's true and Chelsea sign him permanently, It wasn't his fault we paid over the odds for him and that he couldn't quite reach the levels he did at Napoli but he had a terrific first season here and played really well still