When MS Dhoni shocked everybody on December 30 last year by announcing his Test retirement mid-series in Australia to concentrate on his limited-overs cricket and on taking the one-day team forward, he sent India into an uncharted era. To be pedantic, India split the captaincy for a while earlier too, but Dhoni played only 11 Tests under Anil Kumble before assuming full leadership, and both captains in that case were of largely similar temperament and philosophy. Also, Dhoni tasted immediate success in limited-overs cricket, and his Test captaincy was a natural progression.
This now is new. Dhoni is looking to extend his one-day career; he is going to play on at least until the World T20 in 2016. More importantly in the current scenario, the senior, more established captain has the lesser job and will be spending significantly less time with the team than Virat Kohli. Captains the world over relinquish the reins of ODI sides first. Misbah-ul-Haq plays Tests and Azhar Ali leads Pakistan in the one-dayers. Ditto Alastair Cook and Eoin Morgan. Not with Dhoni and Kohli. Getting the ODI captaincy first gives you a soft launch and you naturally progress to Tests, which are full of possibilities and thus demand more of a captain.
Even more importantly in India's case, the personnel for the teams are similar but the personality and philosophies of the leaders could not be more different. In his first Test as captain - as a stand-in at that - and in the frying pan that is playing in Australia, Kohli opted for pace, pace, pace, and a rookie legspinner ahead of a left-arm spinner many believe to be limited and an offspinner who had been tried without rewards in overseas Tests. The thinking was: fingerspinners don't get wickets in Australia, and Kohli didn't want his spinner to do a mere holding job. Another possible explanation was lack of patience, or trying to pull a rabbit out of the hat with not much to lose because he was supposed to have just one Test as captain back then.
Dhoni is more pragmatic. He has reason to be so. India's fast bowlers and spinners are not accurate away from home. They don't offer him the luxury to attack. Dhoni doesn't rage against the machine. He began to gradually ask less of them. Long before the BCCI sent that press release on December 30, 2014, Dhoni had already resigned as a bowlers' captain in Tests away from home. The Lord's Test, when he asked Ishant Sharma to bowl bouncers in the fourth innings, was one last flicker. In the next Test, hampered by Ishant's injury, Dhoni was back to getting Ravindra Jadeja to bowl 12 overs into the pads of left-hand batsmen with a 6-3 leg-side field in the second session of the first day. As if with Ishant injured, Dhoni was back to being jaded with the bowling.
It is possible Dhoni came to Bangladesh and felt the team had moved on. Maybe that leaves him vulnerable. This is a risk that comes with split captaincy
Kohli is young, he is fresh. He has not led India to away whitewashes. He is not scarred. Something about him says he will refuse to settle for less from his bowlers. He wants his fast bowlers fast. Not just in the first four balls of the over, not just in the first two sessions of the day, not just in the first innings of the Test, not just in the first Test of the series. He wants his spinners to go after wickets. He has said more than once that he is willing to risk a loss for a win. Even in Bangladesh he picked three of the fastest men available to him in the squad. At times Dhoni was happy with just Bhuvneshwar Kumar bowling off a long run.
There is no guarantee Kohli's methods will succeed. They will depend on the execution. And, don't worry, his bowlers will test his patience, but something about him suggests that when the bowlers revert to bowling one bad ball per over, he won't just shrug his shoulders and have fielders following the ball. He will demand more. That's what he said in Australia. "You need composure and character to go out there and say, 'I'm tired, but I need to take two wickets for my team, so I need to bowl at the same pace as my first spell.' That's where character counts. When you're tired and you're down and your team expects you to step up. That's something we've not been able to do in the last couple of years."
The success or failure of the new methods only time will tell, but Kohli does seem to have brought in a new philosophy and has jolted the team out of its comfort zone. It is no longer about just the processes. The new leadership says it is not happy with the right processes if they are not producing the right results. It is about time they began winning away Tests, it says. It is also at odds with the way the ODI captain thinks. There is potential for conflict and confusion, if there isn't some already. The selectors and the board - the latter still finding its feet - can't afford to just sit back and watch. They will need to keep a constant eye on how the team is responding to the two captains. The arrangement can easily go on for too long.
Personally, too, there is scope for unease for the captains. To Dhoni, suddenly the team could feel like a new place with new ideas. If you spend time out of it, it can be even more disorienting. You come back in, lead in a different format while trying to rediscover your own batting, lose a series to Bangladesh, and go against your own nature and first criticise a trusted, consistent and selfless batsman who is batting at an unfamiliar station, and then give the out-and-out fast bowlers a tongue-lashing in public.
Earlier this week the Daily Telegraph published a fascinating conversation between two of England's most celebrated captains, Michael Vaughan and Mike Brearley. They spoke from personal experience and from their experience of people. Talking of the upcoming Ashes, Brearley said it was an advantage that Cook hadn't played ODIs and was fresh, but he also pointed out that the England side had changed during the ODIs.
"It will be difficult for him [Cook] if things don't go well to start with, if he feels they have not got the same spirit in the team as they had in the one-day matches, and if he does not feel quite in charge," Brearley told Vaughan. "Nasser [Hussain] felt that with you when you took over for one-day matches."
Vaughan agreed. "That was in 2003," he said. "I did it differently for the one-day matches, Nasser came in for the Test matches and felt the team had moved on." The arrangement lasted only three Tests.
It is possible Dhoni came to Bangladesh and felt the team had moved on. Maybe that leaves him vulnerable. We don't know what he feels - he will never let us know - but this is a risk that comes with a split captaincy. He is edgier than ever, has got frustrated easily, and has expressed that frustration easily.
What Dhoni said about the fast bowlers - unprovoked - in the final post-match presentation in Bangladesh does not necessarily mean that he and Kohli are at each other's throats, or that Kohli can't wait to assume absolute control of the team, but it puts out in the open a clash of ideologies and philosophies. There is an obvious mutual respect there: Dhoni the captain backed Kohli when everybody wanted him dropped in Australia in 2011-12, and Kohli the batsman has won Dhoni many an ODI off his own bat. Yet they could be pulling the team in different directions.
Kohli himself is yet to win a Test. His ODI form hasn't been great. The selectors probably don't feel comfortable enough to hand the team over entirely to him. They probably want to see more of him as captain.
This is a delicate time for Indian cricket, and decisions to be made now are as important - if not more - as when the four big batsmen had to be phased out. The members of the team, some by making plain their intentions to play on until a certain time, some by not performing well in the series in Bangladesh, have not made it any easier for Sandeep Patil's selection committee.

Sidharth Monga is an assistant editor at ESPNcricinfo