It is a shame, but i feel anyone who thinks Aguero is the same player as he was in 11/12 is blinded by their love for the guy.He's been sensational for us, the most lethal and effective player i've seen in my lifetime.
However, for me, injury after injury after injury has taken its tole on the guy. In a straight line he's still quick, but he can't turn quickly like he used to. His game relies on playing on the shoulder of the defender and he cannot do that effectively as he used to. In addition, in order to protect himself, he avoids running the channels and avoids sprinting at 100% unless he has to. Concerns about injuries have sucked the enjoyment of the game for him. How many times has he been stretchered off in tears? How many times has he hit peak form then been injured.
Aguero was the youngest player to make a debut in the Argentinian Primera (aged 15). Hi's body is different to the likes of Messi - Kun run's heavy, falls heavy, doesn't ride tackles well and he's got bad hamstrings. He's on the way down, PEP knows this, we can all see this and his goal scoring figures (as someone posted above) are not entirely representative of the situation.
In short, he's still a class finisher, but injuries have taken their role.