[pylon500]

Have seen this sort of pad wear before and as mentioned, is usually caused by sticking caliper slide pins,
On some of the cheaper quality cars I've owned (a Mitsubishi in particular) the sticking would also lead to twisting of the caliper unit resulting in severe diagonal wear on the pads
I've only just read this post as I was getting a grinding noise from the front disk, and on inspection found that the inside pad was completely worn but the outside pad still had more than half thickness left.
What I'm suggesting is that if you've worn the outer pad, then the caliper is sliding as it should, but the inner pad may not have been installed correctly and is jamming in the frame so the pistons are pulling the slide caliper across and wearing the outer pad.
Looks like I've gotta look for some new rotors
Arthur