The NFL Competition Committee made it a point of emphasis this offseason to crack down on pass interference and defensive holding penalties after the Seattle Seahawks admitted to holding receivers to prevent touchdowns. When the rule was set it was thought by some that defenses like Seattle would start to get attacked by referees and opposing offenses.
Interestingly enough, the opposite might have happened for Seattle. In 2013, the Seahawks were fourth in the league in defensive holding penalties with 13 and first in defensive pass Interference with 13.
While the Seahawks would have 16 holding penalties in 2014, good for fourth, they had only six pass interference penalties, which was good for a tie for sixth with eight other teams. In fact a number of quality defenses didn't get flagged frequently in 2014. The Chiefs were only flagged five times. The Bills were only flagged seven times. None of the teams that were top 10 vs. the pass had double digit flags for pass interference. The team that had the most flags for pass interference was the Tennessee Titans 13 penalties. The Tennessee Titans were 27th in total defense, so it doesn't look like defenses were getting flags for being good.
Defensive pass interference was actually called less in 2014 than 2013, going from 240 to 206. Defensive holding penalties went up from 313 to 386.
So good pass defenses got busted for holding more, but not for pass interference, which is kind of letting defenses off the hook, seeing as they're preventing touchdowns and are only getting penalized five yards for it, opposed to the much larger ones that come from pass interference penalties.