The strains of captaining an international cricket team, especially one as high-profile as India, can be extremely demanding. For more than one player, it has resulted in a dip in his own performances. MS Dhoni's legend is based on his leading India to victory in many top tournaments - he is the only captain to win all three top ICC events, the World Cup, the World T20 and the Champions Trophy - but equally impressive was the manner in which he ensured his own standards as a batsman stayed high through most of his tenure as captain.
Since he took over as captain in 2007, Dhoni led India in 199 ODIs, and over the nine years he captained, his batting average was an incredibly high 53.92. In every calendar year between 2007 and 2015, his ODI average stayed above 40 - the highest was 70.47 in 2009, and the lowest 40.11 in 2007. Apart from 2009, he also averaged more than 60 in 2012 and 2013, and between 50 and 60 in 2008, 2011 and 2014. His consistency between 2007 and 2015 was mind-boggling, but in 2016 his numbers slipped considerably: in ten innings he scored 278 runs and passed 50 just once.
Even so, the difference between Dhoni's ODI average as captain and not captain is 9.70. Among batsmen who have scored at least 2000 ODI runs as captain and as non-captain, only one player has a higher difference: AB de Villiers averaged 65.92 in ODIs when leading the team, and 45.69 otherwise, which is a difference of 20.23.
It could be argued that Dhoni's higher average as captain was largely due to the huge number of not-outs as a result of his batting lower down the order, but even early in his career, his not-out percentage was fairly high: before becoming captain, his not-out percentage was 25 (19 out of 75 innings); after taking over as captain, it increased to 28%. Even in terms of runs per innings (including all not-outs), Dhoni the captain (RPI 38.79) outdoes Dhoni the non-captain (RPI 33.03).
The difference in averages for batsmen like de Villiers and Dhoni is a far cry from those for some of the other top names in international cricket. Viv Richards, inarguably the greatest ODI batsman of all time, averaged 57.39 when he wasn't captain, but after taking on the leadership role his average dropped to 38.81; he scored more runs in 76 innings when he wasn't captain than he did in 91 innings as captain. Richards' difference is average is the highest among the players who have scored 2000-plus runs as captain and non-captain. The drop was fairly steep for Sachin Tendulkar as well: an average of 37.75 as captain, and 46.16 when he wasn't leading. The numbers are similar for Brian Lara, while Sourav Ganguly was also more prolific when he wasn't leading India.
Dhoni's approach to batting when he was captain was characterised by a measured and level-headed approach, which served India well, especially in run-chases. In successful chases as captain, Dhoni has been unbeaten 26 times in ODIs, which is the highest in ODI history; the next best is 22 by Arjuna Ranatunga, another captain whose calm, unruffled manner in the middle order guided his team to plenty of wins. In fact, the numbers for the two captains are quite similar: they both captained their countries between 190 and 200 times in ODIs, and won about 20 more matches than the next-best captains for their countries. They are Nos. 1 and 2 in terms of most runs scored by captains between positions 5 and 6, and are also among the top four in terms of most Man-of-the-Match awards won by captains - Ranatunga won 19, Dhoni 15.
While Dhoni's ODI match-winning abilities come out strongly in numbers, his stats in T20Is aren't quite as impressive. While no captain has scored as many runs as his 1112, Dhoni's strike rate in T20Is is only a middling 122.60. At Nos. 5 and 6, where he has played 42 of his 63 T20I innings, his strike rate is only 115.33, which is 15th among the 19 batsmen who have played 20 or more innings at those positions. That is probably a key reason why he hasn't won a Man-of-the-Match award in his T20I career of 73 matches. Among captains the most such awards have been won by Mohammad Hafeez - five in 29 games as captain - while Chris Gayle, Shahid Afridi and Daniel Vettori have three awards each.
In T20Is, Dhoni clearly wasn't as big a force as a batsman as some of the other big hitters. In ODIs, though, his skills as a lower-middle-order batsman and finisher can't be questioned. Through most of his career, the added responsibility of captaincy only helped improve Dhoni the batsman. The early indications are that Virat Kohli, his successor, is also built in the same mould.