[some deletions]

Well, we agree on the last part.:-)  One of the basic things you need to 
have in a statistic to be able to predict a player's performance on it
in the future is for there to be a correlation from year to year.  A 
player's batting average is correlated fairly well from year to year.
A player's ability to walk or infielder's Defensive Average are correlated
better.  That is to say, given their past performance in those statistics
we can have a pretty good handle on how they'll do next year.  Put in 
some simple information about aging and you can do even better.  One of 
the basic problems with something like "clutch" batting average - overall
batting average is that the correlation from year to year is almost zero. 
Adding to the sample size doesn't seem to help much.  As a counterexample to 
what you showed, consider the following two players from 1984-1987:

               Non-Clutch                      Clutch
               AB      H       BA              AB      H       BA
 
Maldonado      1060    260     .245            254     78      .307
Lemon          1643    457     .278            256     57      .223

If you had had these two players in 1988, by your logic, in those "clutch"
situations, you'd bat Maldonado for Lemon in a blink of an eye.  Well, in 
1988, Maldonado hit .267 in "non-clutch" and .190 in "clutch", while Lemon
hit .254 in "non-clutch" and .313 in "clutch".  Before you accuse me of 
completely cooking the data, there were 96 players who had 25+ "clutch"
at bats every year from 1984-1988 (according to Elias).  As a simple
measure of clutchness, let's just look at clutch BA-non-clutch BA. If you use 
'84-'87 to predict '88 for those 96 players, you'd find that 27 of the
96 were below league average in that measure both in '84-87 and in '88,
26 were above league average in both periods and the other 43 were 
above in one and below in the other.  If you were just flipping coins,
you'd expect to get 24 above/below in both and 48 that switched.  The
difference between the observed results and the coin flip experiment
is not statisically significant.

BTW, correlating players' _overall_ batting average from '84-'87 with
'88 gives a correlation coefficient of 0.59, which is significant at
something better than the 99.9% confidence level.  Correlating their
(clutch-non-clutch BA) for the same period gives a correlation of 
0.088, significant at no level of any interest.


Actually, it's technically incorrect to say that we can't predict future
clutch performance.  It's more correct to say that we can't predict
future clutch performance with any skill.

Harold