There are a number of entries in the Pitching table that have invalid 0 entries
in the BFP field, where it's fairly clear that the actual value is unknown and
the entries should be nulls. The following seasons have at least some records
with this problem: 1882, 1883, 1886 (just one - smith02, CN2), 1888 - 1902,
1905, and 1906.
Doug