I was changing out the ball joints today and noticed that the front pads on the same side were wearing at a different rate something like the insides had a good % less the the the outsides. Anyone seen this before? Expedition has 187K miles and previous owner had the brakes changed just a little before I purchased it at 149K miles.

 

Its common if the last time they did not replace or clean the slides the pads sit on. Most dont shops dont do this. The other possibility is the caliper is hanging.