Murray will always find it difficult to become world number one. The main reason is 5000 ranking points are up for grabs on clay, and he is not one of the best clay court players. Until he improves his clay court record, it will always be an obstacle. He has to reach finals and win 500 clay court events, until he can do this, he will always struggle. This does not mean he cannot reach World No.1, but it will always be a brief stay, unless he has a stellar season winning three of four slams.
Murray is probably either number one or two on hard court these days with Djokovic, and one or two on grass with Federer. He is number two or three with Djokovic indoors, but on clay he is about five or six compared to Fed and Djoks who are two and three. This may seem nothing is the full context of a season, but at their level of elite tennis, it is massive.
Obviously, this is at present and things can change and often do. Murray can improve his clay court game and it is a surprise to me, how unsuccessful he had been on the surface, considering his type of game. On top of this, I have not accounted for Rafa Nadal, who is of course the greatest clay courter. It is still unclear how he will play when he finally returns. Long layoffs of six months or more do not normally help elite tennis players.
I read with interest Pat Cash's comments about Federer not be considered the greatest tennis player ever. Since I think he is wrong, I will give another reason why Federer is above Laver, who Pat thinks deserves equal standing. Yes, Laver the greatest of his day and according to Cash won over 200 tournaments, to Roger’s 80. The big difference is this, and this is why players now have it far harder than in the past. Now the top players have to play each other, in every tournament, not just the slams. There are no easy rides. It is compulsory for top players to play the Slams and 1000 events; they do not get to cheery pick a surface that suits them best and play the majority of their tennis of that surface.
For Roger to have the success he has had over the period he has had it, against the best players every week; it is incredible. Unfortunately, we will never know whether Laver could match this, but we know Federer has.