I emailed the client and described the two options (option 1: sorting provider results alphabetically and option 2: sorting first by distance and then alphabetically). In an absolutely ~scorching~ less than 2 minute reply from the client, she elected to go with option 2. We think this will help facilitate more conversions by presenting patients with the most relevant results in an organized way.
For anyone facing this dilemma in the future, the winning config we went with looks like this:
"sortBys": [
{
"type": "ENTITY_DISTANCE"
},
{
"direction": "ASC",
"field": "lastName",
"type": "FIELD"
}
],