They are of equal ability
Serve - Safin
ROS - Nalbandian
BH - Safin (not by much though)
FH - Safin
Net game - Safin
Volley - Safin
Touch - even
Improv - Safin
Pass - Safin
Movement - Safin
Speed - Safin
Mental game - Safin
because their peak tennis was equally impressive.
Safin at his peak was able to own Sampras at the US Open, beat Agassi, Ferrero, Kuerten at FO, score wins over peak Federer, Hewitt and Roddick at the AO. Even in 2006 onwards when he was crap he was still able to beat Nalbandian at the US Open, as well as beating Djokovic at Wimbledon 2008. The guy has beaten everyone their is, at the slams no less. What's Nalbandian's best win at a slam? Federer in 2003? Gimme a break!
Fat Dave made Safin look like David Ferrer when it came to application and effort, he could have dominated 2008 if hadn't gotten fat.
Madrid Masters 2007 (start October 15th)
-Beats Djokovic in Semifinal
-Beats Federer in Final
Paris Masters 2007 (start October 27th)
-Beats Federer
-Beats Nadal in Final
Right! So beating Federer, Nadal and Djokovic on their worst surfaces, when they are dead tired at the end of the year is really telling of what he can do all year round? My god! Nalbandian really does enjoy god like status on this board. All because of three tournaments in his whole career! You think Nalbandian could dominate an entire year of tennis? Man, even if he did have the ability, here are just a few reasons why Nalbandian couldn't ever dominate the field.
1) Nalbandian when he wasn't fat couldn't dominate the field. I'd say the competition from 2003-2007 is probably the same as it was in 2008-2010 really. Nalbandian even when he was healthy never showed he could have a year like Federer's 04-07/09, Nadal's 2010 or Djokovic 2011 seasons. We aren't just talking about winning three slams; We are talking about winning literally everything they play and going deep on their weakest surfaces.
2) Indoors and carpet: Indoors isn't 24/7 in tennis and Carpet has been kicked on the circuit for a while now. These are Nalbandian's favourite conditions. You can't say Nalbandian would dominate an entire year because of a surface which is used for two months at the end of the year. Many players aren't that great on carpet. For example, are you going to say 'healthy Nalbandian will beat Federer at Wimbledon' backed up with insufficient arguments such as 'he beat Federer in Paris' to strengthen your claims?
Essentially, that is exactly what you have done. You have found three matches, which Nalbandian has won due to circumstantial evidence (fatigue of the top guys/surface bias/Federer's ankle) and have made him look like a god and have put him up on a pedestal saying 'this is what he can do all year round'. When really, this might have been three tournaments of his best tennis AKA no the norm. Unless you'd like to give a great explanation into why Nalbandian doesn't win many tournaments in the first 10 months of the year?
3) Fitness: You state fitness for sighting why Nalbandian didn't dominate 2008. It's a sport! You can't play lame excuses for a professional athlete, justifying a top players lack of wins due to 'being fat and lazy'. He's a sportsman; You don't get given 'could have done better but couldn't be bothered' cards.
4) This is probably the best argument I can make, Nalbandian, is probably the best choker I have ever seen. Suppose Nalbandian makes the AO final, is he beating Djokovic? Is he really going to beat Nadal at FO and Federer at Wimbledon, although Federer that year was on the decline. Suppose he gets to the finals without choking how long do you think it would take for that legendary thinking of Nalbandian to start getting nervous from a winning position? Would you bet on Nalbandian serving for the match against Nadal at the FO? I wouldn't.
Should Nalbandian have won a slam? Maybe. Would have have dominated a year from 2003-2009 if healthy? Hell no.
Look at those matches and the level of tennis and tell me that isn't some of the absolute greatest tennis you've ever seen. That's what talent means, the level of tennis you're capable of reaching.
Seriously? Talent is not this. Talent is a natural gift for something. Someone like Safin was talented because he could make a slam final beating Roddick at #1 and Agassi at #3 whilst not playing a tournament in 9 months. Safin had to rely on talent - he was injured so much he never got a chance to incorporate talent with hard work and consistency of play. Djokovic, Nadal, Murray and Federer are all products of having a lot of talent whilst being able to work hard. Most of the most talented players have a knack for being lazy - thinking talent is what takes you to the top. Just look at the French crop.
I think the word you are searching for is peak, in your last statement.