Some context: Sir Donald George Bradman, AC (27 August 1908 - 25 February 2001), often referred to as "The Don", was an Australian international cricketer, widely acknowledged as the greatest batsman of all time. Bradman's career Test batting average of 99.94 has been cited as the greatest achievement by any sportsman in any major sport. The story that the young Bradman practised alone with a cricket stump and a golf ball is part of Australian folklore. Bradman's meteoric rise from bush cricket to the Australian Test team took just over two years.
In addition to acting as one of South Australia's delegates to the Board of Control from 1945 to 1980, Bradman was a committee member of the SACA between 1935 and 1986. It is estimated that he attended 1,713 SACA meetings during this half century of service. Aside from two years in the early 1950s, he filled a selector's berth for the Test team between 1936 and 1971.  Cricket saw an increase in defensive play during the 1950s. As a selector, Bradman favoured attacking, positive cricketers who entertained the paying public. He formed an alliance with Australian captain Richie Benaud, seeking more attractive play, with some success. He served two high-profile periods as chairman of the board of Control, in 1960-63 and 1969-72. During the first, he dealt with the growing prevalence of illegal bowling actions in the game, a problem that he adjudged "the most complex I have known in cricket, because it is not a matter of fact but of opinion". The major controversy of his second stint was a proposed tour of Australia by South Africa in 1971-72. On Bradman's recommendation, the series was cancelled. Cricket journalist Michael Coward said of Bradman as an administrator:  Bradman was more than a cricket player nonpareil. He was...an astute and progressive administrator; an expansive thinker, philosopher and writer on the game. Indeed, in some respects, he was as powerful, persuasive and influential a figure off the ground as he was on it.  In the late 1970s, Bradman played an important role during the World Series Cricket schism as a member of a special Australian Cricket Board committee formed to handle the crisis. He was criticised for not airing an opinion, but he dealt with World Series Cricket far more pragmatically than other administrators. Richie Benaud described Bradman as "a brilliant administrator and businessman", warning that he was not to be underestimated. As Australian captain, Ian Chappell fought with Bradman over the issue of player remuneration in the early 1970s and has suggested that Bradman was parsimonious:  I...thought to myself, 'Ian, did you just ask Bradman to fill your wallet with money?' Bradman's harangue confirmed my suspicions that the players were going to have a hard time extracting more money from the ACB.
Did he do anything important as an administrative?
A: 
Some context: Sangakkara was born to Kumari Surangana and Swarnakumara Sangakkara, an attorney-at-law at Matale, Sri Lanka in 1977. His parents settled in Kandy, where he spent his childhood. Sangakkara received his primary and secondary education at Trinity College, Kandy, an independent elite private boys' school situated in the central highlands of Sri Lanka. He has two sisters: Thushari and Saranga, and an elder brother: Vemindra, all who have made national-level achievements during their schooling.
In February 2009, the then captain of the Sri Lankan side, Mahela Jayawardene announced that he would step down from captaincy "in the best interests of the Sri Lankan team". He said he believed that it would give his successor around two years to build up to the 2011 Cricket World Cup. Therefore, at the age of 31 and with the experience of 80 Tests and 246 ODIs, Sangakkara succeeded Jayawardene as Sri Lanka's captain in all formats of the game. His first engagement in the role was the 2009 ICC World Twenty20 hosted by England in June. Sri Lanka became runners-up in the series after winning all the game in group and knock-out stages and being defeated by Pakistan in the final. Sangakkara made 64 not-out in the final, but was unable to take Sri Lanka for the championship. Sri Lanka failed to reach to the knock-out stage of the ICC Champions Trophy in September 2009. The next Indian tour proved to be disastrous for the team, with Sri Lanka being beaten by India in Test series 2-0 and ODI series 3-1.  Sri Lankan team under the captaincy of Sangakkara gained momentum and won the next Tri-series in Bangladesh, Zimbabwe and Sri Lanka, beating India as well. The Sri Lankans' tour of Australia proved to be very successful, in winning both the T20 and ODI series. This was Sri Lanka's first ever series victory in Australia.  A month in advance of the 2011 World Cup in March, Sangakkara decided that he would resign the captaincy after the tournament. Sri Lanka reached the final of the tournament. Throughout the tournament Sangakkara was in prolific form with the bat scoring 465 runs from 9 matches and was the third highest run-scorer behind teammate Tillakaratne Dilshan and India's Sachin Tendulkar. Days after guiding Sri Lanka to the finals of the World Cup, Sangakkara announced to the public he was stepping down as captain of the T20 and ODI teams. He offered to continue as Test captain if deemed necessary for transition to new skipper, but Dilshan was appointed captain across all formats. Reflecting on the decision afterwards, he said that "captaining Sri Lanka is a job that ages you very quickly ... It's rarely a job you will last long in ... I also had a two-year stint, and I enjoyed it at times, certainly on the field where our results showed we were one of the top two sides in the world for one-and-a-half years, especially in the shorter form of the game."  The same year, he was named the ODI Cricketer of the Year at the ICC awards ceremony. In 2012, he was honored as one of the Wisden Cricketers of the Year.
Why did he step down?
A:
captaining Sri Lanka is a job that ages you very quickly ... It's rarely a job you will last long in ...