Off the top of my head, these seem like viable candidates for the Distinguished Performance Award:
Ali Louis Bourzgui, The Who's Tommy
Brian d'Arcy James, Days of Wine and Roses
Cole Escola, Oh Mary
Eden Espinosa, Lempicka
Celia Keenan-Bolger, Mother Play
Kelli O'Hara, Days of Win and Roses
Sarah Paulson, Appropriate
Maryann Plunkett, The Notebook
Gayle Rankin, Cabaret
Eddie Redmayne, Cabaret
Michael Stuhlbarg, Patriots
Jeremy Strong, An Enemy of the People
Kara Young, Purlie Victorious
If they werent already giving Groff or Lange a special award, it feels like they could be contenders. I also dont remember if anyone in my above list has already claimed the award in the past and is therefore ineligible. But Im in between meetings so someone with more time on their hands or a better memory can correct me lol