So what would a finished loss be counted as. You have to separate their wins and losses.
Hendo: 30 wins 16 by finish, 11 losses 4 by finish, I guess you forgot those too.
GSP: 25 wins 13 by finish, 2 losses 2 by finish.
so hendo has 41 fights with 21 decisions. 51% of his fights.
Gsp has 27 fights with 12 decisions. 44% of his fights.
7% difference, so not very much.