Still confused by offensive pass interference? You're not alone

Rob Gronkowski's catch against Luke Kuechly was called back because of offensive pass interference. Fred Kfoury III/Icon Sportswire

The route was a familiar sight to anyone who has watched the New England Patriots on fall Sundays this decade. Tight end Rob Gronkowski lined up in the slot at the 42-yard line. He ran 7 yards to the 35, cut to his right against Carolina Panthers linebacker Luke Kuechly and hauled in quarterback Tom Brady's pass for a 10-yard gain.

This time, however, there was a flag. Referee Jerome Boger had called offensive pass interference (OPI), believing Gronkowski pushed Kuechly during his cut to create separation. The play was a reminder that OPI is one of the most vexing and seemingly random penalties in football, a foul that has been on the uptick this season as evolving offensive schemes stress officials' abilities to monitor receivers.

There were nine OPI penalties in Week 4, on top of 15 in Week 3, and a total of 42 in the first four weeks of the season. That rate puts the NFL past its four-week pace in 2016 (32) and 2015 (38). If it continues, the league would exceed the highest recorded number of OPI fouls in recent history.

For the most part, pass-catchers still hold a substantial rule advantage over the defensive players trying to stop them. For every OPI foul this season, officials have called four for defensive pass interference, defensive holding or illegal contact. But as the chart indicates, OPI was once a relatively rare occurrence, called less than five times per week in the NFL.

In 2014, the NFL shifted in an effort to equalize at least parts of the interaction between receivers and defenders. Via a public point of emphasis, teams were warned that officials would focus on contact that receivers initiated at the top of their routes for signs of a push-off -- precisely what Boger appeared to target Sunday. When you add an increase in teams using "pick plays," essentially designed to be legal pass interference, you get a better idea of why OPI numbers doubled between 2013 and 2014 before falling back slightly.

Pick plays have accounted for what was probably an unanticipated portion of this increase. Short, quick throws have grown increasingly popular in an age of poor pass protection and undertrained quarterbacks. Routes designed for one receiver to knock the coverage off another through "inadvertent" contact have grown in popularity.

The NFL rulebook exempts inadvertent contact, but officials are watching closely for receivers who appear to adjust their direction to ensure contact. They are also trying to strictly enforce another rule that prohibits blocking prior to the pass being thrown 1 yard beyond the line of scrimmage; receivers also can't block while the ball is in the air if they are in the vicinity of the intended receiver.

Other than those blocking edicts, the published rules for pass interference are the same for offensive and defensive players. The standard for a penalty is on plays where contact "significantly hinders an eligible player's opportunity to catch the ball." In the case of OPI, officials focus on Rule 8, Section 5, Article 2(g), which states that it is illegal for a player to initiate "contact with an opponent by shoving or pushing off, thus creating separation"

Is that what Gronkowski did Sunday?

When you look at the replay, you see his left arm raised and in contact with Kuechly's chest area. But did he push off as he made the cut? To me, that is an entirely subjective question. It's fair to ask how frequently similar contact occurs on a standard NFL passing play. On the Fox broadcast, analyst and Hall of Fame quarterback Troy Aikman said: "If you're going to call that, we're going to be here all day."

Speaking Monday morning on WEEI's "Kirk and Callahan Show," Brady said: "I think [Gronkowski] is doing what he’s got to do to get open; there was such minimal contact."

Some of the answers can be found in history. Gronkowski has long been a target of this point of emphasis, dating back to 2015 when he was called for OPI six times. The Patriots were penalized for it a league-high 12 times that season.

Boger, meanwhile, has been particularly active on this front. He and his 2016 crew called OPI an NFL-high 14 times, and his 2017 crew ranks second with six. For perspective, consider that while Boger was calling 14 last season, fellow referee Jeff Triplette called one. Referees Bill Vinovich and John Hussey called three apiece. Further context: Boger's 14 OPI calls in 2016 are double what referee Craig Wrolstad has called since the start of the 2015 season.

Indeed, as we have noted many times before, referee tendencies are real and sometimes carry over from season to season despite the NFL's shuffling of individual crew members. Suffice it to say, the teams whose games Boger is assigned should prepare for a more tightly called game.

"Some weeks you get those calls," Brady said on WEEI. "Some weeks you don't."

To be clear, defensive players have a far greater rule challenge to navigate and are much more likely to be called for a penalty while covering on a pass play. Many of us pay more attention to the plight of offensive players, for fantasy or other reasons, but generally speaking they still have a decided advantage. The NFL, however, appears intent once again on limiting those boundaries.