Quite certain it's for Greg Williard, a 24-year veteran of the league.
According to
Awareness Ribbons Meanings and Colors, purple does mean pancreatic cancer:
Quote:
Purple Ribbon:
Meaning: This color is a symbol of pancreatic cancer, testicular cancer, thyroid cancer, domestic violence, ADD, alzheimer's, religious tolerance, animal abuse, the victims of 9/11 including the police and firefighters, Crohn's disease and colitis, cystic fibrosis, lupus, leimyosarcoma, and fibromyalgia
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Additionally, officials working the 2012 finals wore a #57 patch on their jerseys.