Leach, the innovator of the "air-raid offense" died at 61 on Monday after complications related to a heart condition.
McNeill sat down with ABC11 Sports Anchor Travon Miles to reflect on the life of his friend and former colleague.
"Mike was an innovator. He was, I would call him brilliant and genius," McNeill said. "And also had an innocence about him ... he was very inquisitive."
McNeill said Leach had his beliefs and didn't waver from them -- in football and in life. He was a great family man, McNeill said, and he made his assistants plan time with their families.
Watch the full interview in the media player above.