Because of copyright-trademark-whatever considerations both the official team names and the real player names were removed from versions >= 1.6.2 and 1.7.2.
For versions < 1.9.0, you can
download them from here
(a simple tar.bz2 archive).
Recommended destination directory is $HOME/.bygfoot/text_files.
Users who have the Bygfoot source package can also use the
bygfoot-update script to download and unpack the archive.
Users who have versions >= 1.9.0 have to use the bygfoot-update
script to get official names. Since the script isn't included
in the Windows package, you can also
get the official names here. Unpack
into the support_files directory (or into $HOME/.bygfoot-1.9
if you use a Linux package other than the binary package).