This season he's not even playing all the time as a front man, because Florin Andone, a romanian as myself, is their striker. Perez is playing in a Miki/ Alexis role and considering how poor Depor has been this season, it certainly isn't fair, or accurate, to say that he's not clinical.
You can't do everything by yourself when the whole squad is crap, can you? Considering the club he's playing for and not always as a striker, I'd say that 4 goals and 3 assists in this season is a decent number so far and there's still a little over three months to go until it ends.
As a comparison, Andone scored six so far.
So what if he's 29? Diego Milito and Di Natale were also late bloomers and were hitting it big at this age or even older.
He will be back. Not exactly going well.