Physically he's incomparable to the player that captained Chelsea to the League in 2004/05. He's a yard slower, doesn't have anything like the same spring, and athletically he's just not the same. He says he hasn't been injury free for 5 years or more, and I think that, along with 50+ games a season, has taken it's toll on him.
I just think as phenomenal as their reading of the game is, Vidic and Terry are too easily exposed by speed and need a team set-up in a certain way to be successful, too dependent on the right partner, to be hailed as the untouchable players that they are. If someone built like Kompany or Djourou can learn to read the game anything like as well as Terry or Vidic can then we're talking about a player that would warrant the hype.