EVERYTHING about Diablo is local. The beef, the the pickles, even the hot sauce I noticed was made in Flagstaff. The organic ice cream for their kick-ass shakes is from Straus Family Creamery (in California, hmm, not very local but way good). Even their cash-only policy is technically local (the menu points out, correctly, that transaction fees go to a bank that is not very local at all).
The burger was great, cooked to temp (using a thermometer) on a flame grill with (local) lava rocks, and served on an English muffin that has Diablo's logo branded on top (above). I'm not a fan of the English muffin at all for a burger mostly because they taste sour and funky, and this one imploded under the juice of this perfectly cooked burger. A toasted white squishy would have been the way to go and I assume they chose the muffin as an excellent surface for their 'brand'. I asked for American cheese and was quickly reminded that there was no 'local' American. I settled for a local cheddar with local bacon.
If you are looking for a seriously local burger Diablo is no joke. Their beef comes from cattle raised 40 miles from Flagstaff. Just don't ask for American cheese.