I disagree that Dhoni and McCullum are overrated at all. Dhoni has shown his maturity as a batsmen in the past year, as he has been able to pace his innings, and go beserk if his team needs it of him. He doesn't have a particularly compact or elegant technique, but has great mental strength, which causes him to lapse in concentration much less than other batsman.
McCullum of course goes beserk regardless of the situation, which disadvantages him a little, but he is backed by strength, decent technique, and good timing. However, I'm not sure if he's capable of playing a mature innings if his team requires it.
Of course, Sangakarra is hugely UNDERratted in the one-day form of the game. He is probably the perfect batsmen, but has been off-form of late, but you can see from his IPL innings that he can call upon his brilliant technique, buckets of experience, exquisite timing, and elegant strokes to utterly smash the bowlers all around the park if he decides to throw caution to the wind and back himself.
Of course, in recent times(for Sri Lanka, not Kings XI) the situation has not let him play naturally, it has required him to play anchor man, which he has done brilliantly.
All three of these wiki-batsman are absolutely outstanding, in fact all three of these players would rate in the top twenty batsman in the world, regardless of their wicketkeeping.
