If you think about it, 'represent AL in a store I'd never been to, for a bunch of players I'd never met before' is a pretty reasonable Local Coordinator job description, which is why that should probably Be A Thing That's Part Of The Job.
There is a fairly extensive document telling LCs what they are supposed to do if they volunteer, but running games at stores isn't part of that. LCs are there to assist stores in finding DMs when asked, but they are not a free DMing core to tap for anyone that wants a DM (there simple are not enough LCs for that). I will also note that 'represent AL in a store I'd never been to, for a bunch of players I'd never met before' is not the same as DMing; though many DM because they wish too. They are expected to go to stores and talk to people about the AL and assist store organizers in getting things going.
Read more:
http://www.enworld.org/forum/showth...-GM-on-D-amp-D-Encounters/page3#ixzz3nQRAddct
Local coordinators are expected to:
Help maintain the League’s social media presence by:
o Posting on the League’s global, regional, and local websites;
o Answering League-related questions on such websites; and
o Helping to maintain and expand the League’s wiki.
Support stores in their areas by:
o Visiting them at least once a month to get to know players, DMs, organizers, and store owners and to answer their questions; (frequency varies with size of coverage area and number of stores)
o Advertising League-related store events in social media and at conventions;
o Helping stores find players, DMs, and organizers; and
o Helping stores join Wizards Play Network (WPN)
Support local and regional conventions by:
o Identifying conventions that offer, or might want to offer League games;
o Helping conventions to find organizers and DMs;
o Advertising League games at conventions in social media;
o Helping conventions to advertise in social media; and
o Attending conventions.