If number of success is taken to be criteria for defining great captain then there would only one great captain (that is Ricky Pointing). People may point at his ashes defeats as a captain but he still remains great captain if we take above version.
Let's define - great captain:-the guy who takes responsibility in difficult situation, stands for his mates irrespective of their form , identifies the distinguished talents in fellow players .
Arjuna Ranatunga may not have players like Warne , Mcgrath ,Gilchrist ,Martyn or Hayden but he proved to the world that it's not the great individual build great team in 1996 world cup. He always stood for teammates, the best example i can think of is, when murali was accused for chucking by the umpires then he fought against umpires, media and gave confidence to murali . People may say, it’s not a big issue but why didn't captains of shoaib akthar or Harbhajan singh ever support them. Arjuna did find talent in sanath Jayasuriya and promoted him to the top of the order which payed off for both him and sanath .
Kapil dev didn't have joel garner, marshall nor vivian richards in his side but his attitude to fight made him win 1983 world cup. Remember when india were 5 wickets down in a do or die match, he came in and hit 175* which changed whole scenerio of the match. In the final, it was he who took great catch of sir vivian.
Captains become great only if they are willing to take risks at crucial junctions of the match and showing confidence in his teammates.
Ricky pointing is a good captain and great player (may be greatest) but he can never be a great captain. Yes,he has great succes rate in tests and ODI's but he just lead a team with all time greats . He is suffering defeats because the greats have left his team.