Wow. I would have thought that you, more than most, would know that snap count is hardly the be all/end all when it comes to the talent of a player.
Ninkovich is better at setting the edge than either TBC or Cunningham. Ninkovich is also better in coverage than either TBC or Cunningham. Where Ninkovich isn't as good is rushing the passer. Which he wasn't called upon to do, much of. And, since the Pats were in their Nickel package more than their base 3-4, that takes Ninkovich off the field. When the Pats were running their 2-4-5 Nickle, they put Cunningham and TBC on the field much of the time. When they ran the 3-3-5, Guyton was on the field as an OLB with Moore rushing the passer either with his hand down or from a 2 point stance.
Cunningham has the potential to move ahead of Ninkovich in terms of over-all impact. But as many noted, TBC wasn't worth much on the field and many feel that his days as a Pat are done.
Oh.. Since you love stats so much.. Lets look at this:
TBC - 36 Solo, 9 ast, 5 sacks, 2 TFL, 1 FF
Cunningham - 27 solo, 7 ast, 1 sack, 5 TFL, 1 PD, 2FF
Ninkovich - 45 solo, 17 ast, 4 sacks, 4 TFL, 4 PD, 2 INT, 3 Fumble recovries.
So, less plays but more production. I know what that tells me.