It seems like the Patriots and the Red Sox both take contract negotiations really personally.And between them they've won 6 rings in the last 12 years.
The Pats can get away with it because they have the greatest coach in NFL history and one of the greatest qbs. Even losing a very talented player in Collins for essentially nothing, I still think they're the best team in the league this year.
The Sox can get away with it because they do a great job acquiring and developing prospects and they can spend more money than 25 teams in the league.
Also it's entirely possible that there would have been no room for a deal with Lester if the Sox had been willing to negotiate with him, and I think it's likely Collins was going to the highest bidder, which wouldn't be the Pats, but in general it seems like they end up going for some vengeful tactics in the middle that IMO cross a line.