I believe I'm pretty realistic about the lifespan of a professional athlete. Look at Agassi for instance -- made a slam at age 35, most likely b/c he wasted the first 5 years of his career (as Mats Wilander noted).
Agassi was an extremely rare case in this modern age. The wild out of nowhere exception rather than the rule. Perhaps Serena will be some amazing exception too but I wouldnt bet on it. Anyway you should know full well by now the feelings of the mens field that Federer rose amongst and dominated, the same field Agassi had these late career runs you speak of.
Serena is similar, having (as you noted) basically wasted from July 2003 thru January 2007, so on that basis, I would expect her to have an career end at an older age than most athletes -- IF SHE TAKES IT SERIOUSLY -- which is a BIG if.
I guess that is possible. We will have to wait and see. She did contend regularly in 2004 so I dont think she was asleep just yet. Just didnt have the confidence and had some bad luck. I think 2005 (after Australia) and 2006 were the only years she sort of tanked away on purpose.
About Tiger in golf, there has never been in that game a comparable physical specimen -- he basically forced all top players to have physical trainers, which was unheard of in 1996. Tiger is already 33; there is no reason he can't be competitive (i.e. a threat to win one major/year) for another 20 years given his physique, mental toughness and mental edge he has over the entire field (and will have as he starts playing against players who were kids when he won his first Masters -- similar to the psychological edge Graf had near the end of her career against young players). That's not unreasonably given that people in markedly worse shape threatened regularly in majors in their late 30s e/early 40s, and even someone like Singh -- who as great as his body has held up is not anywhere physically in Tiger's league -- is still a force in his mid-40s. Not unreasonable at all that Tiger's prime could exceed Singh's by 10 years.
For starters I dont consider Singh in his prime anymore at all. I believe the last year of his prime was 2005. He has missed 5 or 6 cuts of majors since the start of 2006 and hasnt had a top 10 in a major for over 3 years now. He had a decent year last year outside the majors I guess, but last year was a joke with Tiger injured then out, all the so called big stars not at their best or having poor years, and the lack of top end quality or impressive up and coming stars of the current overall field outside Tiger to begin with.
No I certainly do not believe Tigers prime will last 10 years longer than Singh at all. I think that is ridiculous. 10 years is a huge amount of time, even in golf. Also Singh has not had any major injuries, Tiger has already had a major knee surgery in his early 30s. I already think he is a little past his best already in fact though he is still the best player for now (like I said I do believe the current field outside of Tiger is very weak anyway).
Regarding Serena vs. Navratilova, the women's field has only been extremely weak since Henin retired -- the fields from 2006 till Henin's retirement were better than anything Navratilova faced in the 80s until Graf emerged in 87. Plus, the game has progressed significantly and is much more difficult in Serena's era -- you don't see moonballers win slams anymore, or even make slam finals unlike the 80s and much of the early 90s (that's not to say that prime Navratilova wouldn't much on the current tour, but its still a fact).
The only regular moonballer that won a slam was Conchita Martinez. Jankovic is closer to a moonballer than any of the slam winners of the last 25 years, and while she didnt win a slam she was last year year end #1.
The fields have been weak since 2006 atleast. In 2006 the only meaningful players were Henin, Mauresmo, and Sharapova. In 2007 the only meaningful players were Henin, Serena, and Venus on fast courts. Anyway Serena only won 1 slam in 2006-2007 so whether the fields were weak since 2006 or just since 2008 dont matter much in her case. Moonballing or not you will be hard pressed to find many weaker major winners than no variety pusher Myskina, headcase without even exceptional talent Kuznetsova, and forehand only (and not even that amazing a forehand) Ivanovic who have accounted for 4 slams between them in the last 5 years. A marginal contender like Mauresmo was also able to have her greatest year ever at 27.
That said I do agree Navratilovas competition from 82-86 was extremely weak. Shriver was the perennial World #4. Austin was pretty much finished after 1981 due to injuries though she played a bit of part time tennis in 82 and 83 where she was already a total shadow of her old self (probably was playing at the level of a Maleeva sister at best those two years). Jaeger who was never that good anyway was done after 1983. Mandlikova was great when she was on, but I find overrated since people seem to judge only her top level which she hit 10% of the time in her prime, and not her consistency or overall sustained level of tennis. Evert was already past her prime a bit when Navratilova began to dominate. Graf and Sabatini were obviously extremely young and pre primed those years, though in 86 a 16 year old Graf was pretty good but still nowhere near her prime level of 88-96. Turnbull was a decent but not great player in her prime who was early 30s by then. Kohde Kilsch, Bunge, Hanika, Jordan, are not even worth noting other than a 15 year old Graf was already slapping them around. So yeah upon second though I am not sure Serenas competition is a weakness compared to Martina atleast, especialy since the field in 1999-2003 was actually pretty good.
