Clarke cut short his acceptance speech, saying he was 'getting too emotional again' - after his well-publicised response to the retirement of former Australian captain Ricky Ponting in December.
"I don't really know (why) to be honest," Clarke told reporters at Melbourne's Crown Casino.
"I have been quite emotional over the past couple of months, which is unusual for me.
"Tonight's probably the only night through the year that you get to reflect on what's been a great 12 months for the boys from the Australian cricket team.
"Reflecting on Ricky (Ponting) and Michael Hussey's retirements, to see Glenn McGrath being inducted into the Hall of Fame … it's a build-up of a lot of things to be honest.
"But it's unlike me and hopefully you never get to see that again," he said.
The Australian captain scored 1,588 runs in Test and ODI cricket in the qualifying period - from February 25, 2012 to January 28, 2013.
The 31-year-old polled 198 votes to finish 33 ahead of joint runners up Mike Hussey and Shane Watson.
Clarke also won the medal in 2005, jointly with Ponting in 2009 and last year.
He said the 2013 award meant as much to him as his first but stressed his focus was on delivering success for Australia during upcoming tours to India and England.
"To me I would love to see the Australian cricket team standing on a stage in the near future winning the best sporting team in the country or the best sporting team in the world."
"When I first came into the Australian team, I was part of such a very special team and we had so many great players and we were the number one Test and one-day team in the world for a long period.
"Those memories stick fondly in the front of my mind and I want this current Australian team to have that same feeling and be able to walk out onto the field and know what it's like to be the best."
Clarke said his brilliant calendar year was a result of years of hard work, which started when he was dropped from the Australian Test team in 2005.
"It was a tough time when I got dropped from the Test team, but I think that's probably the time in my life when I realised I had to work a lot harder than I was to stay in the Australian team," Clarke said.
"When I got dropped, scoring one run seemed a long way away, let alone winning an AB Medal.
"When I first came into the Australian team, the senior players regularly spoke to me about not being in such a rush, being more patient and trying to be as consistent as I could through the good and bad times.
"As a young player with no patience and always in a rush, that was quite difficult.
"When I got dropped it made me stop and reflect on the areas I wasn't giving 100 percent … and I think that changed my attitude.
"The scary thing about getting dropped is you never know if you're going to play again for Australia and credit to all the boys who've been dropped, come back and get a second chance to play for Australia. It's not an easy thing to do."
The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of Cricket Australia