This is Chip Kelly. Former coach of the Oregon Ducks and (as of today) current coach of the Philadelphia Eagles.
If you Google the Kelly, Google's "knowledge box" will give you some quick info on him. Including his nickname...
How did the name come about? Well thankfully the greatest compendium of human knowledge, Urban Dictionary, has it covered:
I wonder if these shirts will come with Kelly to Philadelphia.
My biggest issue is that it's Big Balls Chip and not Big Balls Kelly. Big Balls Kelly sounds like one of Al Capone's friends. Big Balls Chip sounds like some guy at the local golf course with a medical issue.