Starting in 2008, our fielding stats merge two sources which lead to some discrepancies between the two sources:
Full-season stats as would be available in the Baseball Guides, in the Baseball Encyclopedias, or on MLB.com. Next is play-by-play stats as from Retrosheet.org.
The problem is that recordkeeping for fielding stats previous to 1988 was generally poor (or less important) and there are many, many, many cases where the stats compiled from the play-by-play accounts do not match those that were compiled and reported at the end of the season. Generally, the play-by-play is more accurate, but there are errors in both, so in the merging this could lead to discrepancies.
The places where this could lead to discrepancies:
Career Outfield Stats - players who played in the outfield prior to 1956 may have incomplete career stats for LF, CF, RF.
Outfield Stats - from 1956 to 1995, stats for LF, CF, and RF come from play-by-play and stats for OF come from end-of-season records (except for innings and GS which come from pbp). In some cases the numbers for LF, CF, RF may not match with the OF totals.
Outfield Stats, two - from 1996 to 2007, stats for OF come from play-by-play and stats for LF, CF, and RF come from end of season records. Generally these years have stats that are pretty solid.
GS and Innings Played - from 1956 to 1999, these stats come from play-by-play accounts, so there may be cases where a player has more GS than G (for instance if he was injured in the top of the first while at bat).
SB, CS, and WP data for catchers - from 1956 to 2007, these stats come from play-by-play accounts. There are 200 games out (from 1955 to 1973) of 100,000 where the play-by-play account is missing and we have only box score summaries. In some cases we have SB and CS data for those games, but not every case, so these numbers may not be 100% for those years.
For further questions or comments, send us a note.