What is the g_old column in the batting table?

I googled a bit but couldn't find the answer, and the documentation only say "G_old          old Games Played field". Specifically, why does it differ from g_batting for players who never pitched?

Example:
select *
  from batting b
  where g_batting <> g_old
    and not exists
      (select null
        from pitching p
        where b.playerid = p.playerid
          and b.yearid = p.yearid
          and b.teamid = p.teamid
          and b.stint = p.stint)

Gives these player years:
greenkh01    2006    1    SDN    NL
bellira01    1996    1    ATL    NL
benjami01    1994    1    SFN    NL
cartega01    1979    1    MON    NL
clarkje01    1990    1    SDN    NL
mccraqu01    1997    1    COL    NL
mearepa01    2001    1    PIT    NL
redmomi01    2002    1    FLO    NL
sakatle01    1982    1    BAL    AL
spierbi01    1993    1    ML4    AL
thomaga01    1978    2    NYA    AL

Looking at the game logs, I can't figure out what happened here that caused g_batting and g_old to differ.

/Micke