I don't think skipping AAA is totally uncommon. Certainly isn't here in DC. Usually due to injuries. I remember Difo was called up from AA after a spate of injuries.
Used to happen a lot more often than it does. MLB teams used to do that all the time early part of the century. Past few years was also because the AAA team was in Fresno. They put guys they wanted easy access to in AA so they could get here more quickly.
