I can name probably 20 or 30 players who have the game. Whether they have all the other things at each of those tournaments, I can't answer that. Complete game, confidence, patience, guts, positive attitude, the mental cap-acity to adjust to conditions. Scooping up all four quarters of the Slam requires that comprehensive package and more. Superb putting, particularly on fast greens, is essential.
Experience is an asset.
Luck helps, too, in regard to the roll of your ball and others'. And you really can't skank it around and win any of them. Various traits apply to certain tournaments. Somebody who is very long may be able to win the Masters but not the U.S. Open. Somebody who hits the ball very low may be able to win the British Open but not the Masters.