SoS, please show me where I said Dhoni is the greatest captain ever. I had shown why I think Dhoni's the best captain in the world cricket atm.
Secondly, Gambhir scoring runs in the 2nd Test has nothing to do with Dhoni, Dhoni has added the belief to the players and is making them perform well, as to reach the team goal, World Number 1 status. That doesn't mean if he's not playing that the team will go down like a lead balloon.
Also, if Dhoni has a good side, it's hardly his fault. India has had bad sides in the past, now we have a very good side, so it's Dhoni's good fortune.