I see this thread is still going strong. :lol:
I know my words will fall largely on deaf ears around here, but in short, my take is that if you put them on clay in the same era (more or less equalizing for conditions, opponents, etc.) Muster would be better than Fed for about a year or two, but Fed due to his superior consistency would end up with more impressive career stats.
One thing that seems lost on most, and which you can check by perusing the return stats now available on the ATP site (at least since 1991, except for a few missing matches mostly from the DC, Olympics, etc.), is that most elite clay-courters have at least a year or two in which they win over 40% of their return games on the surface. In fact it's almost eerie how this rule seems to hold up after all these years (my guess is that the pre-'91 stats aren't much different). Muster reached that mark in '95, at 42.9%, and just barely in '96 at 40.1%. Fed OTOH never came close, topping out at 35.2% in '05.
Now the Fed camp would point out that this discrepancy is offset by his superior serve, and on first glance they would seem right on the mark, as he usually won 85% of his service games or more on clay, including a whopping 89.6% in '09 (which barely was able to withstand a rather subpar 25.8% of return games won in his successful FO run). By contrast the best Muster could muster up (heh heh, get it) was 83.0% in '93, followed closely by 82.9% in '96.
But there are a few caveats. First of all, it's a myth that today's players are returning better than ever, or at the very least this common wisdom is not supported by the stats, which clearly show, quite on the contrary, that they're holding serve with more ease than perhaps ever. This is due to many factors but most of all to the greater spin allowed by today's more "advanced" racquets, which is reflected in the increases over the years in just about every service stat across the board (1st-serve %, % of serve points and games won, and so on).
Even so, the upticks in service stats have been quite dramatic on clay compared to those on grass and HCs, which have been smaller and more incremental. And this trend still holds true even when you compare the early '00s stats to those from the more recent years. In fact I'm pretty sure this is why, again contrary to popular belief, that the top 10 servers of the '00s actually won a higher % of service games than their '90s predecessors overall, 87.1% vs. 86.0%, and why players won 90% or more of their service games only 7 times in the '90s (the total number of players is 3, with only Sampras achieving the feat more than once), as opposed to a whopping 20 times in the '00s. Take out clay and I suspect that the differences between the two decades would not be so eye-popping.
Now the Fed camp might retort that such increases would bring down Muster's own %s of return games won, and yes they would, but probably not enough to matter much. First of all, as I pointed out earlier on this very thread %s of service games won and of return games won aren't created equal, because a player's decline (or, conversely, his improvement) tends to have nearly twice as much impact on the latter than on the former. And this all makes sense once you consider that players generally win a much higher % of games on their serve than on return. So Fed's superiority on serve is more than offset by Muster's on return.
Perhaps even more importantly, though, you have to consider Muster's style of play, which is that of a genuine clay-court specialist and not a modified HC game usually played by Fed (or Djoko for that matter). That is, greater shot tolerance and patience, and probably a higher average topspin rate (off both wings) generally conducive to clay-court tennis. It's fashionable for the pundits to say today's courts play more or less the same, while conveniently ignoring the documented facts that grass courts still produce by far the highest rates of service holds and clay the least ratios of free points on serve, and that players like Roddick and even Murray have a hell of a hard time on clay while attacking players (relatively speaking) like Fed tend to do well on grass. So it's quite likely that it's not the courts that have "slowed down" today's game (again a myth according to the stats), but that it's the players who don't adjust as much as they should. Another case in point: a clay-courter like Ferrer, despite having fewer weapons than Muster (not to mention other former greats like Bruguera and Ferrero), is able to succeed and finish among the best in return stats on clay (granted Ferru has a great return across all surfaces).
And you can see the same story in Fedal's famous encounters. One thing that sticks out to me after nearly all their FO meetings (and indeed long thereafter) is this insistence on the part of some Fed fans that their guy would've won or at least made the matches competitive had he continued to play his best, without realizing why he has time and again failed to do so and why indeed he has yet to push Rafa to a 5th set. Again that's no accident and due in great part to Rafa's grinding style of play, which is generally favored on clay over HC-style tennis.
Of course Muster is no Nadal, and I'm pretty sure that if they were to switch places Thomas wouldn't be able to match Rafa's otherworldly stats (win-loss %, %s of games won, etc.) in their respective peak year (or two). Still I do think he'd win a similar % of return games and a higher % of service games, again given these facts I just laid out. Having said that, Muster at the same time never quite managed to bulldoze through his opposition at RG like Courier in '92 or Bruguera in '93. (In fact, except for his final with Courier Sergei's game W/L% at the '93 FO would've been up there with anyone's including Borg's and Rafa's, and even with it his % stands at
#14 in all of the Open era.) We all like to say our favorite player would win many more majors if not for this player or that circumstance, but the more I study tennis history the more it becomes clear to me that overall competition across the eras remains more or less similar, and it's generally implausible that a one-time Slammer would somehow become a 3-4 time major champion when transported to another era (and taking the place of his counterpart in said era, which generally is ignored in these cross-era comparisons), and vice versa.
All of which is a long-winded way of saying I don't think either Muster or Fed would win many more than 1 FO in any era. But what about their matchup against each other, you say? It's always a bad idea to compare two players by how they'd do against each other, but my picks are Thomas at their respective peak, Fed outside of their primes. In the former scenario Fed would make things interesting by coming to the net often, because as Mustard often points out passing shots were not Muster's strength and Fed would seek to use this weakness of Thomas' to his advantage. But it's one thing to attack the net so relentlessly in a given match, but to do it day after day takes a toll on you unless it's your preferred style of play, which isn't the case for Fed. That's the reason why Fed has rarely been able to reproduce his form in his '06 Rome against Rafa, and over a series of say 10 matches or more I suspect the percentages would gradually shift in Muster's favor. Outside of his '95 or perhaps '96 form, though, Muster would not have the overwhelming advantage on return over Fed, so in this case I do think Fed would be able to prevail more often than not. I suspect their results against the rest of the field would follow a similar arc: favoring Muster at his best, Fed over the rest of their careers. The irony prompted by looking at Muster's title haul is that his detractors tend to focus on his MM events, while his truly great run in '95-'96 tends to be shortchanged--the very opposite of the facile implications of his output.
So who is better? (Which really is the main question, not the disingenuous/misguided one posed by the OP.) I really don't see the point of trying to rank these two, because one can make a case either way. If pushed I'd rank them about equal, though I'm sure that's not going to deter most of you from bickering over the tiniest perceived slights and misconceptions and pleading for your guy. Carry on.