Q. How much does he have left in the tank?

A. Here are Griffey's comps from b-ref.com, from age 39 to end of career:

 Sim  Player              From  To Yrs   G    AB    R    H   2B  3B  HR  RBI  BB   SO    BA   OBP   SLG   SB   CS OPS+
+---++-------------------+---------+--+----+-----+----+----+---+---+---+----+----+----+-----+-----+-----+----+---+----+
      Ken Griffey         Was not playing, is not playing, or has not yet played at this age.
 887* Frank Robinson      1975-1976  2   85   185   24   43   5   0  12   34   40   27  .232  .366  .454    0   0  136
 870* Willie Mays         1970-1973  4  429  1348  235  357  60   8  60  191  278  308  .265  .391  .455   33   8  135
 869  Sammy Sosa          Was not playing, is not playing, or has not yet played at this age.
 861  Rafael Palmeiro     2004-2005  2  264   919  115  240  42   0  41  148  129  104  .261  .351  .441    4   1  108
 828  Gary Sheffield      2008-2008  1  114   418   52   94  16   0  19   57   58   83  .225  .326  .400    9   2   91
 826* Mel Ott             Was not playing, is not playing, or has not yet played at this age.
 811  Barry Bonds         2004-2007  4  417  1122  286  340  65   3 104  254  488  152  .303  .519  .644   14   1  198
 785* Mike Schmidt        1989-1989  1   42   148   19   30   7   0   6   28   21   17  .203  .297  .372    0   1   91
 783* Eddie Murray        1995-1997  3  320  1169  150  325  49   1  46  179  115  178  .278  .338  .440   10   1   98
 773* Reggie Jackson      1985-1987  3  390  1215  171  291  53   3  60  186  203  350  .240  .351  .436    4   4  114
      Ken Griffey         Was not playing, is not playing, or has not yet played at this age.
+---++-------------------+---------+--+----+-----+----+----+---+---+---+----+----+----+-----+-----+-----+----+---+----+
 Average of all 8 Players            2  257   815  131  215  37   1  43  134  166  152  .264  .392  .474    9   2  127

They averaged two more seasons of 127 OPS+ production. That's a lot more than I expected, even from inner-circle HOF'ers, at ages 39 and 40. The list isn't comprised of good comps for Griffey. You wouldn't be able to find ten good comparisons to Ken Griffey Junior.

Still, it's instructive to go through line-by-line. Let's start plowing through the comps individually. Here are the problematic comps first:

..............

Sammy Sosa was way done at age 35. Use your own judgment as to whether Sosa is a legit comp for these other "Naturals".

You know what? I'm not taking a vote as to whether Sosa or Raffy Palmeiro belong on this list. Executive Decision: these two ain't on here. :- ) But for the record, Raffy had a 108 OPS+ at age 39 and at 40.

These two guys are a pox on the list.

................

Garry Sheffield I'll buy, with reluctance, in the interests of objectivity (I don't want to cherrypick the list). Sheff was real good, real young, and arguably a "Natural." Sheff was great until age 36 and has been mediocre since.

I'm guessing that amigos who dislike the idea of Griffey being here, will plump for Sheffield as an appropriate comp. I would agree there are some good reasons to match the two up, after discarding personalities.

................

Mel Ott, a white guy who was perhaps baseball's most park-generated player, was a superstar until age 36 and then practically stopped playing. I don't know how much he drank, though the Giants of the era were infamous for the carousing and "likker."

You're going to find a similar line for Mickey Mantle -- not on b-ref.com's list -- awesome until 36 and just stopped playing. Mantle is famous for the 6-oz tumblers of brandy, his Breakfast of Champions.

FWIW, I can attest to you kiddies that age 37 is a great number to pick, if you're going to pick one age at which your legs don't bounce back any more. For me it was 37 exactly: I took off down the line in slo-pitch and for absolutely no reason, blew the hammy....

................

Bonds, hilariously, posted a 263 OPS+ at age 39 and was also historically-great at 40, 41 and 42. He doesn't belong in this set of age comps, but then neither do Sosa or Ott, so...

...............

Mike Schmidt, a right-handed white guy with a thick chest and short limbs (IIRC), was great through age 37, good at 38 and then done. You don't comp Schmidt to Griffey and Mays, but then, how many guys are there to pick from with 500 homers, 1,500 RBI, 1,000 walks and all that stuff?

..............

Eddie Murray. Back to a reasonable comp. Eddie was great through age 34, good from 35 to 39, and then done.

.........................

Reggie Jackson is a better comp than Ott, Sosa, Palmeiro or probably Sheffield. Reggie! was a legit MOTO hitter at 39, was a quality hitter at 40, and was mediocre at 41.

.........................

Reggie isn't a case against Junior at age 39, and Barry Bonds? We can confidently assume that Barry would have been good to SOME degree or another at ages 39 or 40. Funny milkshakes don't turn you from Richie Sexson into Babe-Ruth-Plus at age 42. Or there would have been a lot of other guys who were great at 40.

Considering where Sosa, Raffy etc. wound up, it's a very intriguing question how good Bonds would have been if he were natural. He might have been as good as Aaron, Mays and Rose at their ages. I dunno.

Anyway, if the above guys were the group you were going with, you'd say, stay away from Griff at age 39. But another comp-group exists...

Cheers,

jemanji