The importance of defining innings in a batsman's growth can not be overstated. Consider 2 examples and how they have affected two of India's most important players. 2 years ago, on July 19, 2007 MS Dhoni came into bat against England in the second Innings of the Lords Test, and scored an unbeaten 76 to save the match. India had all but lost the match by then, and were really saved by rain, but for Dhoni it became a defining innings in more ways than one. Until then he had been purely perceived as a blaster with questionable abilities and usefulness in Tests. He had big hitting big scores in limited overs cricket, but that day he buckled down and played an innings of great responsibility, nudging around without any risky shots.
In ODIs, until Aug 2007, Dhoni had 2302 runs at an average of ~47 from 76 matches with 3 hundreds. Since that innings till date Dhoni has 1983 runs @ 52.18 from 55 matches with 1 hundred, against Hong Kong. Did that test innings make him a better limited overs player? Not really - what happened was that the team management began to trust him more as a player and a finisher. This in turn has led to him curbing his instincts more and more and instead nudging and rotating strike more efficiently to let the other "unreliable" big hitters like Yuvi and Yusuf take the risks. His average and his strike rate have not suffered because he is still one of the best runners between the wickets in this Indian side. Moreover, he was made captain and the added responsibility from that coupled with his workload as wicketkeeper has led to a totally changed player today. So, today when journalists naively ask him where his big shots have gone, I am surprised he does not throw the mike at them. You try doing what he does - captain of India in all 3 formats, wicketkeeper and reliable lower order finisher - and then switch effortlessly to high risk big hitting mode. It is beyond stupid and to Dhoni's immense credit that he has not lost his cool yet doing all of this plus dealing with the Indian media circus.
Consider also Gautam Gambhir. He started his ODI career in April 2003 and until Feb 2008 he had played 47 matches at an average of 35.33, but he had hundreds only against Bangladesh and Sri lanka, and his average against every other country was in the low to mid 20s. On Feb 24, 2008 he came in to bat against Australia at Sydney in the VB series and scored an excellent 113. He was never the same after that. His average since that match till date is 46.22, and he has 3 hundreds. Further his average against every country is now in the mid-to-high 30s and his whole demeanor has changed completely. Until that innings he was filled with self doubt and played with a scowl. That one score in a key match against the world's best, away from home, changed him totally as a batsman and he has not looked back since.
The key question in all this analysis is whether Dhoni can bring his shots back. I think this is all based on his role in the side. As long as his role remains one of a stabiliser/finisher, he cannot really change his game much. He is just too good in that role, so I do not see anyone else taking over the responsibility, unless we start playing him purely as a batsman in limited overs and have either Karthik or Parthiv as the wicketkeeper. That is a remote possibility, since we don't really have an allrounder in the side to ensure 4 frontline bowlers.
There has been a lot of criticism directed at Dhoni for denying Raina and Yuvi practice by coming in at 3 in the T20 world cup. This was part of a clear plan and it is again unfair to blame him. If a wicket fell during the powerplay, Raina went in, but if a wicket fell after the first 6 overs, Dhoni would be sent in. That is exactly what happened. If Raina, with 200+ ODIs under his belt cannot adjust to fast rising balls, it is unfair to blame Dhoni. The leading Indian scorer in the IPL should not need match practice for 2 matches against minnows to get acclimated. Raina was in form and should have played better than he did. Dhoni played his role, Raina failed in his. Simple as that.