To be honest I do not think that Shogun has suffered the quantity of damage that someone like Wand has suffered.
I do not remember very very good each one of his fights, but from what I remember, the only 2 fights when he took a looot of damage was in the Jones and the Hendo bouts.
He also had damage against Forrest and Lil Nog but it was not like in the Jones/Hendo bouts.
It looks that cardio has became a huge issue for him in the past years. The only fight that lasted many minutes and Shogun looked OK was the first Machida fight.
He gassed against Forrest (1st fight), Coleman, Jones, Hendo, Vera.
In the other fights he won in 3 minutes.
The fact that he has had a lot of knee surgeries obviously affect him, but I also think that maybe he does not train as hard as before. He comes to fight with a gut!!
Yesterday he did not has his most impressive performance, but still he won easily. He dominated the first 3 rounds and finished in th 4th. He was never in any kind of big trouble.