I think you need to reread the entire thread. I started by stating the reasons why I don't believe McCourty is elite impact defender which had nothing to do with the Pats defense in aggregate. Instead it was an opinion formed purely based on the player's performance on the field. Feel free to debate me on the merits of that.
A later point I made was that if you aggregate up people's (on this site) opinions of the defense, the actual performance did not meet the sum of the perceived pieces. I feel like McCourty is one of those overrated pieces. I love the Pats, but if I'm going to say Brady is one of the best QB's ever, BB is one of the best coaches ever, Gronk is the best TE in the league, Revis is a future HOF CB, Jamie Collins is one of the best athletes in the NFL, ect. At some point the rational side of my mind needs to balance some of the reasons why we don't blow everyone out by 40 points every week. Something has to give. After watching enough film I found that I don't think McCourty's actual play holds up to what his reputation says it is.
Ultimately the Pats didn't have the best defense in the NFL last season, you can slice it however you'd want, but ultimately the standard doesn't hold up. I love how talented we are, but the roster as presently constructed isn't sustainable forever. I'd love McCourty back, but ultimately I think he's closer to Antoine Bethea and Rashad Jones rather than ETIII or Smith. Not everyone on the Pats is elite, and in this case I think the Pats need to hold firm on this valuation.