I look at this as raw data, nothing more. You have to find out when the losses happened. Did they happen before a player started peaking? Or well after a players peak? Where did the losses happen?
I would put more importance on the when. When you look at all Fed's losses, it becomes obvious that most of them happened before 2003, when he was still "Baby Fed", in 2013, some in 2008 (mono). When you strip the rest of it away you end up with his one weakness, his H2H against Nadal. And even that needs to be examined by surface.
Interesting question.
Federer breached into Top10 in 2002, before that he was only an Junge. His Achilles heels are indeed Nadal, Djokovic and Murray. His win-loss rate is over 90% since 2004, against non-Big4 opponents.
Nadal rivalry is the bloodiest, since the spaniard got him knocked out in a variety of surfaces (like Djokovic) and without losing many battles (as suffered Novak and Andy):
2004 — *Nad 1 x 0 Fed — clay x -
2005 — Nad 1 x 1 Fed — clay x hard
2006 — *Nad 4 x 2 Fed — hard/clay x hard/grass
2007 — Nad 2 x 3 Fed* — clay x clay/grass
2008 — *Nad 4 x 0 Fed — grass/clay x -
2009 — Nad 1 x 1 Fed — hard x clay (the opposite lol)
2010 — Nad 1 x 1 Fed — clay x hard
2011 — *Nad 3 x 0 Fed — hard/clay x hard
2012 — Nad 1 x 1 Fed — hard x hard
2013 — *Nad 3 x 0 Fed — hard/clay x -
2014 — *Nad 1 x 0 Fed — hard x -
2015 — Nad 0 x 1 Fed* — - x hard
Besides Nadal, the other 2 are formidable rivals as well:
—Murray is one of the few 3 to have >10 victories over Federer, being since always ahead of Roger, until 2014.
—Djokovic is, along with Nadal, the only player to have won >20 against the Swiss. As a matter of fact the Serb is the only payer to heave defeated all Big4, more than 20 times and in all surfaces.
Without Big 4, « theoretically » be understood , Federer would have amassed:
— 11 year-end #1s and
— near 26 GSs…