In most H2Hs I've observed that the ability of the players to read the opponent's serve plays a huge role, huger than the aspects of the rallies. It's really strange but this ability varies a lot : it's far from being as easy as to say "X is a great server, Y is a poor returner then ...", it really depends who is against who.
For Fed against Ferrer, Söderling and Davydenko (also Del Potro), his alternance with the sliced backhand also plays an important role.
True, this is the case in many matchups.
I'm a Fedfan but I disagree with the final part of your comment.
7 out of 13 matches between Fed and Ferrer were until the beginning of 2007 when Ferrer was not at his best yet and Fed was in his prime.
Since then, the 2 matches they played on clay were both in Madrid, which is Fed's best clay tournament, esp. this year with the blue clay (the previous one was in 2010 and was actually tight).
Ferrer is too good on clay for Fed to feel that comfortable against him. 3-1 against Djokovic on clay (and Djoko struggled in his only win in Madrid 2011), come on ...
The other 4 matches they played after Hamburg 2007 were for 3 of them in the WTF (indoors) and Cincy, Fed's favorite tournaments.
Besides, Ferrer has won 4 (and not 3 as you said) sets in the 7 last matches they played. Ferrer has improved (notably the DTL backhands) and also he has found better tactics against Fed in their last matches, especially the forehand DTL moonballs to his backhand (followed by a crosscourt forehand sometimes).
Then no, I disagree that this H2H can only get worse, I rather think this H2H is too favourable for Fed at the moment.
So you think Ferrer will improve the H2H? I must disagree, I fully believe Federer will win any future match between them on any surface. The Djokovic argument is void; Nole lets him play the game he likes, with long grinding rallies. Federer doesn't at all.
Nishikori leads 3-1 against Berdych, 2-0 against Tsonga, I don't think it's a matter of power.
People usually mix them all under the name of "big hitters" but imo, and I observed it makes a big difference in the way the H2Hs are with many players, Del Po and Söderling are very different from Tsonga and Berdych, in the fact that they make fewer errors and their game is based on constant power and depth (you talked a little bit about depth about Del Po and that's very important) rather than accelerations like Tsonga and Berdych. Besides, Del Po and Söderling use some spin whereas Tsonga and especially Berdych (Cilic as well) play much flatter.
Besides, contrary to you, I think Nishikori has the ability to defeat Del Po in the future, just needs to adapt his strategy, I saw their match in Wimbledon and it was far from easy for Del Po and the commentator also said that Nishikori didn't use the right strategy.
Del Potro has far more power than Berdych and Tsonga, especially off the FH. Kei can dictate player against those two, against Del Potro he can't, he gets pushed back every time JMDP gets a full swing on a FH.
Oh Kei could surely get a win some time in the future, but he needs another strategy for sure; with his limited defensive abilities (despite his quickness around the court), rallying with Delpo from the back isn't a good idea at all.
Cilic doesn't like great defenders and playaers who have good depth, I also remember it was his main problem against Del Po.
True. Good defenders make him go for too much and pile on the errors. Good returners can also exploit his serve even more.