I think Gavin just said that the Commander deck faces are professors, not that they're the main ones.
Willowdusk is a dryad of unknown age. She was recruited as a Witherbloom professor when students got lost in Detention Bog and she led them back while teaching them botany on the way.
Osgir is "obsessed with relics of the past" and kept getting in trouble as a student for hoarding the best finds. His specialty now is "duplicative restoration".
Zaffai is a musician whose power also effects weather phenomena. Maestro of the Orchestra of the Arcane, an elite extracurricular for the top Prismari students, who always perform outside and fills the skies with elemental magic.
Adrix and Nev teach together and grew up in the mana-rich waters of Pinsari Isles. They could see the patterns of tides and were able to predict a tsunami and save lives.
Breena has a talent of incepting ideas through speech. She backs up her rhetoric with scrolls of ink magic.
In addition, the five student characters:
Zimone of Quandrix: math prodigy whose grandmother was a professor who disappeared
Dina of Witherbloom: blunt dryad with salamander familiar
Rootha of Prismari: perfectionist artist who wants to make her own reputation
Quintorius of Lorehold: loxodon who wants to discover history of his race
Killian of Silverquill: student whose dad is a professor with high expectations of him