All of Jones previous title opponents save Chael were incredible strikers. The key to Gus's performance wasn't his striking but his speed, chin and reach. Now you tell me how many HW's have all those traits.
I'll preface this by saying that this is what I noticed before going into Jones vs Gus and as a result, lost all my vCash by betting on Gus.
Jon Jones' title fights:
Cheal Sonnen - came up from MW
Vitor Belfort - came up from MW
Rashad Evans - always considered a small LHW, dropping to MW
Lyoto Machida - would consider him a legit LHW, but dropping to MW
Quinton Jackson - legit LHW but at the tail end of his career, dropped more fights than he's won since losing the LHW belt.
Muaricio Rua - legit LHW but at the tail end of his career, dropped more fights than he's won since losing the LHW belt.
Gus isn't significantly faster than the top HWs. Long, lanky guys are never fast. They can beat you to the punch with the jab because of their reach, but they're not faster strikers. Guys with shorter arms are always faster finishing their combos or drills on the pads because their limbs don't have to travel as far when they're in range.
There are plenty of guys at HW who are just as fast as Gus (given less endurance) at comparable reach. They're just much, much stronger because 1.) they're naturally bigger at fight time and 2.) they're not cutting weight until the day before the fight.
If speed were all that mattered, then any one of the top LHWs could walk into HW and claim the belt? Why don't they? Because size fucking matters.
At HW, Jones gets bullied the same way he bullies most other LHWs. He doesn't have the height and leverage to do what he does to LHW fighters at HW. With one or two exceptions, everyone at HW is just as tall as him, has just as much core and upper body strength and carries significantly more lower body strength.