Very good post as usual Matt.
I agree with what you're saying, and disagree slightly at the same time.
I think Buff is a top pairing guy. Is he in the realm of Suter or Weber? No. But when you look at the 30 teams, not every team is blessed with a Suter or a Weber. The guys who can play 25 minutes plus a night, and have very little negatives to their games. Heck, even Suter has a negative if you consider his lack of offensive contribution.
I think baring a few examples, the majority of top pairing D men in the league carry a combo of positive qualities and negative. Letang, Karlsson, and Subban put up great offense, but none of them are the guys you want on the ice down a man in the last 2 minutes of the game. Their defensive game is not strong enough. Keith is an excellent skating D man, but can be inconsistent as well, and isn't a monster physically. Etc. And some teams don't even have quality 1st pairing guys.
Buff may have more of a total swing from bad to good in his game I will agree with you there. I.E. When he is on, he is simply dominant. There have been some games this year he has flat out won for us. He simply owned the Flyers IMO. But his "bad Buff" games can be lower than you would like from your top guy. The game is Chicago was terrible for a junior B player. I think we have seen much more good than bad this year, but that trend is troubling for sure. You add in his age, his contract, his size and his shape which could be worrisome as he approaches 30 and beyond, and there are some question marks there to be sure.
I could be wrong, and I guess we will see IF Buff ever gets dealt, but I think with the way he has played on D in the last few years, what he brings to a team, and the premium on right handed PMD, I think his value in the league is pretty high. He is simply too much of a mouth watering player for a GM (like a Holmgren) to look at and think that with Buff and some of his forwards, he could help take that team into the playoffs.
One thing I think with Buff's value correlates to the $ that professional athletes make. A professional athlete doesn't make the obscene amount of money because of the value that they bring to society, they make the obscene amount of money they make because of the scarcity of the talent they posses relative to every other person in the world. I think Buff's value is somewhat like that as well. There really are no other D men in the league that bring to the table what Buff brings. I really don't see any other D man in the league that brings Buff's skating, offense, passing, AND size to the table. My hypothesis is that this scarcity of talent is what should enable Buff to have a very high trade value.