Home Run Kings

The table below describes the number of home runs hit by Sammy Sosa, Ken Griffey Jr., and Mark McGwire over their career. Which baseball player has the best chance to break the all time home run record of 755 by Hank Aaron? Explain your reasoning.
  


Year Sosa
Born
11/12/68
Griffey
Born
11/21/69
McGwire
Born
10/1/63
1986      3
1987      49
1988     32
1989 4 16 33
1990 15 22 39
1991 10 22 22
1992 8 27 42
1993 33 45 9
1994 25 40 9
1995 36 17 39
1996 40 49 52
1997 36 56 58
1998 66 56 70
1999 63 48 65
2000 50 40 32

Henry Aaron played for 23 years. I took the current totals for each player and got an average number of HR's per season. I then extended the average over the rest of the 23 year period. Using that method, they'd all break 755 HRs.

Click here to see a table that shows a comparison of HRs  by season for Sosa, Griffey, McQwire, and Aaron. (This may take a few seconds to load... )

What about.....?

Will McGwire be able to play that long?
Can we assume that each player will hit the average number of HRs per year they have established up until now?
What other factors could contribute to hitting more or less HRs for each player?