63175's point still stands, that is basically meaningless.
With a straight-up mutual option (no buyout if the team declines it), it's obviously rarely going to be exercised.
But occasionally it'll land in a range where the option is for roughly what the player and team both think he'll get on the open market but neither wants to take the risk of being wrong. And the most frequent time that happens is with old, injury-risk hitters who can still hit a little but often can't stay healthy - for example, Aramis Ramirez and Jason Giambi had mutual options that both sides picked up near the ends of their careers. Kendrick is in the sweet spot for that, though I suspect the team declines unless the murmurs are that the DH is coming back next year.