Watching Dhoni captain India over the last couple of years, a psychologist would probably describe his performance as schizophrenic.
There's no doubt he's been two skippers in one; on tour in England and in Australia he was totally reactive to the point of appearing comatose, but in the
first two Tests of the current series he's been pro-active and, for him, quite animated.
Only he knows if the reason behind his lacklustre overseas performance was disillusionment with selections or just resignation to India's fate. There's no doubt that having an attack, he felt was extremely competitive against a mediocre Australia side, has re-energised Dhoni.
Therein lies the crux --- the primary task of a captain is to make his side better. Nobody is saying a captain can make an ordinary side great but he can improve it. He has to attempt to get the best out of his side and in hard times, that requires a lot of work. Dhoni didn't perform that task in either England or Australia.
In the current series against Australia, he's been full of ideas.
However, it's one thing to inspire players when the team is going well but it takes a special leader to achieve that distinction when a match is running the opposition's way.
Dhoni came to the job full of ideas and enthusiasm and most importantly, he had the team whole-heartedly behind him. A good captain can fail if he doesn't have the team's support and conversely, an ordinary skipper can succeed if everyone is pulling in the same direction.
With more time in the job, Dhoni appears to have stagnated as a Test captain, while still performing at a high level in the shorter forms of the game. His failure to progress as a Test leader isn't because he doesn't have the full support of his team since he has won, and always held, the respect of his players.
It could be that Dhoni has just worn down as a Test captain. He's been doing the job in all three forms for about five years and also captains his IPL side and that's a hell of a mental load.
That's where a captain gets worn down - in the mind. A captain who spends six hours in the field, plotting downfalls and planning strategies is mentally worn to a frazzle by the end of the day. To do all that plus the demanding wicket-keeping job is a Herculean effort and Dhoni's fitness and resilience are amazing.
Dhoni is probably ready to be relieved of some of the load. He's better at short-form captaincy but showed with his daring counter-attacking innings in Chennai he still has the enthusiasm for the longer contest when the mood hits him. He's now the most successful India Test captain but the next series is overseas and that's when the other Dhoni could re-appear. The tour of South Africa may well decide Dhoni's future as Test captain.