The year in NFL officiating was marked by more than the usual number of complaints about missed calls, bad calls and replay interpretations. It was stacked with unprecedented administration brought on by the largest number of rule changes, amid the highest degree of referee turnover, in recent memory.

The NFL competition committee manipulated the new helmet rule, roughing the passer and offensive holding in-season. The league office fired an official for the first time in its modern era, and it moved away from an assignment system that spread officials evenly among teams and games.

"I worked for five different vice presidents of officiating," said retired referee Terry McAulay, now an NBC Sports analyst. "And every single one of them had a year where the noise was higher than the other years. Sometimes it's just because of the way the ball bounces. But I think this year the word 'unprecedented' comes to mind in describing officiating. There were so many things that none of us have ever seen before."

With the regular season behind us, let's grade the effectiveness of the rule changes implemented last spring, updating our midseason evaluation.

Helmet rule

Years of biomechanical research and alarm over the catastrophic spinal injury of Pittsburgh Steelers linebacker Ryan Shazier led the NFL to prohibit players from lowering their helmets to initiate contact with an opponent. That's what the rule stated. But after excessive preseason enforcement (51 flags in the opening two weeks), a competition committee clarification rolled back the flag totals. McAulay termed it a "complete dismantling." Officials threw 19 flags all season, all but one against defensive players. The league office, however, issued 28 fines and 139 warning letters as part of what it considered a long-term education process. The intent of the rule -- minimizing head and neck injuries -- was good. The decision to pull back enforcement was preferable to the chaotic alternative showcased in the preseason. But in the end, the NFL chose not to enforce a major rule in real time. That strikes at the credibility of the game. Rules should be enforced, suspended or repealed. Grade: C

Catch rule

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The league discarded years of concerns about unintended consequences and new controversies, changing the rule that had reversed a handful of high-profile catches. Receivers no longer need to maintain control of the ball throughout the process of going to the ground. Instead, they must complete a football move or have enough time to do so. There was a rise in "cheap" catches, and the possibility of additional fumbles could have created a safety issue. But those ramifications didn't register with fans, players or coaches as much as seeing an obvious catch overruled. Given that context, the NFL accomplished its mission. Grade: A

Slight movement of the ball

This new interpretation made as big of an impact on officiating the catch as the rule change itself. The competition committee added this line to the case book: "If the ball moves within control of the receiver, he is deemed not to have lost control of the ball, and it is a completed pass." That tweak delivered a much-desired effect to replay review, preventing the technical reversals based on slight movement that we saw often in 2017. Overall, replay reviews and reversals were both down in 2018, and reviews decreased by more than 20 percent. Grade: A

Body weight into the QB

What once appeared to be a narrow effort to prevent Aaron Rodgers-like injuries exploded into the story of the first month of the season. After asking officials to redouble efforts to identify and penalize instances of falling on quarterbacks with most or all of a player’s body weight, the NFL watched as roughing the passer penalties of all types increased. There were 34 in the first three weeks of the season, prompting a competition committee clarification. Penalties dropped immediately but then hit another blip (25 during Weeks 13-15) before ending the season at 119. This episode represented one of the worst overreactions we’ve seen in recent years, one that prompted laughable flags that damaged the credibility of officiating. Some players blamed it for their letting up on obvious sack opportunities, while others were injured in an attempt to alter their trajectories. Grade: D

Alterations to the kickoff

Faced with the potential elimination of the kickoff, a committee of special-teams coaches devised schematic changes to minimize high-velocity collisions. Most notable: No two-man wedges by the return team and no running start for the kicking team. A midseason analysis of injuries, speed and collisions left league executives pleased and planning to move on to overhauling the punt in 2019. But the changes further encouraged teams to take touchbacks and eschew returns. The leaguewide touchback percentage rose from 56.6 to 60.8, and the return percentage dropped from 40.6 to 36.8. The rule also made onside kicks more difficult; only four of 52 were recovered all season (and playoff teams went 0-for-2 on wild-card weekend). The kickoff appears saved, but at what cost? Grade: C

Illegal contact emphasis

A 4.9 percent drop in 2017 scoring prompted a competition committee search for causes. Among its findings was a large decrease in flags for illegal contact, which covers contact against eligible receivers before the ball is thrown (and 5 or more yards beyond the line of scrimmage). This emphasis resulted in an 84 percent increase in illegal contact flags in 2018, from 38 to 70, resuming the penalty frequency from earlier this decade. Although the delays and automatic first downs raised frustration from fans and teams, the shift helped deliver the desired outcome. Scoring jumped 7.4 percent to 46.6 points per game, the second-highest average in history, and the league set records for composite completion percentage (64.9) and touchdown passes (847). Grade: B

Ejections by the New York office

Owners empowered senior vice president of officiating Al Riveron to order ejections for a deserving act of unsportsmanlike conduct. In its official statistics, the league didn't differentiate referee-generated ejections from Riveron's decisions, but we know of at least one from Week 5: Kansas City Chiefs defensive tackle Chris Jones, who threw a punch during an extra point attempt. Overall, however, ejections became a much more common tool in managing behavior and safety. Officials ejected 20 players, more than in any season since at least 2001 and probably ever. This is a big deal but was necessary to demonstrate sincerity in rule enforcement. Ejecting a prominent player in a 16-game season can have a direct impact on wins and losses. Grade: B

Marking headfirst slides

The league aligned headfirst slides with feetfirst slides in an important way. Players who do either are viewed to have given themselves up, and the ball is marked wherever it was when they were judged to be down -- whether or not they were touched by the defense. This created the potential for marking the ball a yard or more behind where forward progress stopped. In one notable example, Cincinnati Bengals quarterback Jeff Driskel lost a touchdown in early December when replay showed his knee down before he reached the ball over the goal line. This was a rare change that benefited the defense, and it was fair. Otherwise, quarterbacks were getting credit for yards when defenders let up in fear of an unnecessary roughness penalty. Grade: B

No PATs at the end of regulation

Before this season, the NFL required teams to kick an extra point (or go for two points) even when a touchdown on the final play of regulation ensured a victory. But after a series of chaotic attempts to clear fields and pull teams back together, the league dropped that requirement for 2018. It arose on one notable occasion. In Week 16, the Tennessee Titans didn't kick an extra point after cornerback Malcolm Butler's 56-yard touchdown return of an interception. The play gave the Titans a 25-16 victory over the Washington Redskins. (The point spread for the game in some places was Tennessee -10.) Grade: A (unless you bet Tennessee to cover)

Officiating assignment shift

With a record four rookie referees in the mix this season, the NFL made a notable in-season administrative change to the way it assigns referees and crews. It busted one norm in Week 11, by mixing three crews for a much-hyped Monday night game between the Chiefs and Los Angeles Rams. More quietly, it ensured that veteran referee Bill Vinovich -- whose crew threw the fewest flags in the NFL -- worked six Sunday night games. Historically, referees work one Sunday night and one Monday night game at most per season. "It came down to having a lot of inexperienced individuals out there officiating," former officiating supervisor Jim Daopoulos said. McAulay suggested that kind of differentiation would likely cause "a huge sense of frustration" among officials. An attempt to minimize mistakes on the big stage is admirable, but the unavoidable message to teams and fans of the other games is an unmistakable relegation to second class. The NFL has no one but itself to blame for experience-related performance issues. Grade: C