Every sports fan worth his salt has gone through it. It feels a little inbred. It feels a whole lot wrong. You try to look for the silver linings, but you know you won't fully embrace it until midway through the next season when he makes a big play.
It's that whole thing of when your team signs or trades for a player that made his bones with one of your fiercest rivals. Double the sentiment when that certain player was recognized as the No. 1 instigator/A-hole on that certain team you've despised for years.
Bryan Cox, the biggest AFC East whore this side of Keith Byars, was despised by Patriots, Jets and Bills fans alike from 1991-95 when he was the Bill Laimbeer to Dan Marino's Isiah Thomas as a part of some very good Miami Dolphins teams. He was arguably the "No. 1 bad ass" in the league at the time due to the antics below: The time when he gave the entire Ralph Wilson Stadium crowd a DOUBLE bird as he walked onto the field and the time he tried to fight the entire Cincinnati Bengals roster.
When you have a guy like that on your team, you adore him. Cox absolutely gave the Dolphins swagger on defense and - for a brief period - made the previously "soft" Dolphins look rugged. Cox would play with the Chicago Bears in 1996 and 1997 before heading back to the AFC East to join Bill Parcells and the Jets. Then Jets defensive coordinator Bill Belichick must have liked what he saw out of Cox as he brought him to Foxboro in 2001.
Patriots fans weren't thrilled with the move at the time. Cox was thought of as someone who hadn't won jack in the league. A typically loud-mouthed punk who was everything that was wrong with '90s pro football.
Cox broke his leg in an October game against the chop-blocking Broncos that year and vowed revenge on Denver guard Dan Neil.
"I don't care if it takes the rest of my career," Cox said at the time. "If I ever play that guy [again], he's going to have a blown-out knee, and I don't care who knows it."
It was feared at the time that Cox's entire career was in jeopardy. Whether it was a motivational tool or not, Cox returned to play for the Patriots just five weeks after his right leg snapped. The Patriots did not lose a game the rest of the way en route to a Super Bowl win. Cox made five tackles during the near two-month stretch where he was playing on a broken leg.
Cox is now the defensive line coach with the Atlanta Falcons and has been the most entertaining figure thus far on HBOs inside training camp show, "Hard Knocks." The highlights include him talking about how every man has a vice (his is smoking cigars), warning his players to keep the f*** away from his daughter and how he began having sexual intercourse with women when he was 10-years-old.
Follow Metro Boston sports editor Matt Burke on Twitter:@BurkeMetroBOS