Who told you rankings say player A is better than player B?!
Rankings tell you how a player has done in terms of results in the past 52 weeks.
Right now nadal has had better results in tournaments in the past 52 weeks. After the AO Ferrer will have better results in tournaments in the past 52 weeks. Seems pretty accurate to me.
All the Fedtards that were defending him when I and others claimed that Djokovic was clearly the better player during the fall of 2012. But no, 'Rankings don't lie'
Even your last statement is questionable. The Nadal case is a bit tricky to use, since he well, hardly played at all. But what if Player A has 3 slams and Player B has 1 or zero, but better results in other tournaments and thus more points. I wouldn't call that Player B has performed better in the past 52 weeks.
Rankings reward slams with more points, but this is still nowhere representative to importance for my liking. No way do 2 masters equal 1 slam.