Depends.
If Juve don't sign another forward and Llorente is playing with Vucinic, he will be there primarily as a finisher and so he would need to get up closer to 20 goals in all competitions for it to be considered a good season. .
If he was paired with Higuain, Llorente would have more of a target man, link-up type role, with Higuain as the finisher, so 10 goals might be a good return from Llorente in that situation.
If Llorente is paired with Jovetic, Llorente's role would be somewhere in between and you'd look for his goal return to be in-keeping with that.
If Juve don't sign another forward and Llorente is playing with Vucinic, he will be there primarily as a finisher and so he would need to get up closer to 20 goals in all competitions for it to be considered a good season. .
If he was paired with Higuain, Llorente would have more of a target man, link-up type role, with Higuain as the finisher, so 10 goals might be a good return from Llorente in that situation.
If Llorente is paired with Jovetic, Llorente's role would be somewhere in between and you'd look for his goal return to be in-keeping with that.
