Had Mayo been drafted later, we'd be having a different conversation. He was unfortunately wasted during his best years on horrible defenses. Statistically, he blows HT out of the water. In fact, HT only moved to ILB when both Mayo and Spikes left.
He would've been easily regarded as the Pats best MLB of all time had his career started when their defense started to turn the corner in 2012-2013 when Talib was acquired. Mayo was cooked by 2013.
It's really a shame his name is forgotten when talking about LB's just because he didn't win a Super Bowl.