Robert Kraft is extremely upset with how the league tried to put a bow on DeflateGate. Not only does he believe the investigation was a sham, he believes the punishment far exceeds the alleged crime.
According to Bleacher Reports' Jason Cole, "multiple sources have indicated that New England Patriots owner Robert Kraft is strongly considering a lawsuit against the NFL." Cole puts a caveat on that statement by noting those same sources are trying to bring Kraft back from the ledge.
Any lawsuit against the league, according to these sources, will likely be fruitless in the long run. It seems highly unlikely that the Patriots will be able to recuperate their lost 2016 1st round pick, barring a game-changing reaction by Kraft or the league.
CBS Sports' Jason La Canfora adds that the Patriots executives still believe this scandal was a set-up and they're "fuming" at the severity of the punishment.
The general feeling is that the suspension to Tom Brady was expected, as well as the subsequent set of appeals. The penalty against the Patriots franchise- $1 million, a 2016 1st round pick, and a 2017 4th round pick- was far-reaching and unprecedented.
If the league penalized just Brady, or just the team, it's unlikely that such an aggressive response would have taken place. Instead, the NFL now has an angry trio of Brady, Kraft, and Bill Belichick to deal with for the 2015 season.