The game against the Colts the Patriots clearly cheated. It is beyond reasonable that 11 of 12 footballs are 2psi less than the rule allows. Especially since the 12th football of regulation weight is the football used for kicking as you want the football inflated properly. But using fumbles as proof of long term violation is tough because their are too many factors to consider. Patriots are a pass heavy team and have been for a long time. They use multiple RB's and a fresh RB is less likely to fumble than one RB used heavily throughout the game due to mental and physical fatigue. WR's fumble but are less likely than RB's. An under-inflated ball is easier to grip so it would be interesting to see how WR's who left have fared on their new teams and if any returned later, after playing poorly on new team, to play well for the Patriots. Since 2007 has Tom Brady's completion % and interception ratio on the road improved drastically? All these things could be explained by an under-inflated but not definitively.