as ++Eily said while I was typing this up: unless you throw away the 'nick' element somehow, it's 6 elements. I tried on an ancient linux perl and on a recent windows strawberry perl, and both gave the counts (6) I would expect:

perl -le 'print $]; @a = split/,/,"nick,1,2,,56,88"; print scalar @a' 
+; perl -V:osname
5.008005
6
osname='linux';
[download]

and

perl -le "print $]; @a=split/,/,'nick,1,2,,56,88'; print scalar @a" & 
+perl -V:osname
5.026002
6
osname='MSWin32';
[download]

edit: and I also meant to say, the proper way to parse CSV is with Text::CSV