On mine, the entire assembly was too far to one side, and the hard application of brakes was actually pushing the rotor into the caliper housing itself. (The pad adjustment on that side was completely backed off) I had to loosen the two allen head bolts on the backside and slide the whole mechanism over about a millimetre or two to centre the disc in the opening again. Since then, no worries.
When I have replaced pads, the interior of that mechanism seemed pretty simple to me; caliper, pad, spring, pad, caliper. Would never presume to second-guess the mechanic, but I can't fathom how or why he would need to pry the pads apart.
Unless your brakes are substantially different than mine. ('05 Fire Mountain)
Hope this may be helpful.