I didn't see this discussed elsewhere but this is from the ESPN article on this:
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Anil Jain, a distinguished professor in the Michigan State Department of Computer Science and Engineering and a nationally recognized facial recognition expert, believes it's "highly likely" that the images of the man wearing sunglasses and a hat on the Central Michigan sideline and of Stalions on the Michigan sideline are the same person.
At ESPN's request, Jain and Steven Grosz, a doctoral student, used state-of-the-art commercial face recognition system to compare the two photographs. The system compared the images based on several facial characteristics -- Jain said they are trade secrets -- to provide a similarity score in the range of zero to 1. The higher the similarity score, the more likely the two faces being compared are the same person.
Jain said the system produced a similarity score of 0.6 when comparing the two photographs. To validate that score, Jain and Grosz compared Stalions' photo to a database of more than 4,500 photos of white males.
"The reason why it's 0.6 is because there's a disguise," Jain told ESPN. "If I take an identical photo, it would be 1. Even changes in the pose, illumination, expression, sunglasses, the match will never be perfect. Based on this analysis, the two images are of the same person with high confidence."