Our weekly attempt to expose and explore the gray area involved in officiating NFL games. Sunday suggestions welcome via Twitter (@SeifertESPN). For all Inside Slant posts, including the weekly Officiating Review, follow this link.

Play: Baltimore Ravens receiver Steve Smith penalized for offensive pass interference, overturning a go-ahead touchdown with 32 seconds remaining

Referee: Clete Blakeman

Analysis: Blakeman's crew entered Week 8 calling the NFL's fewest penalties per game (12, declined and accepted). It had called only one offensive pass inference penalty this season, but there was no hesitation Sunday in making a decision that wiped out a game-changing play.

The Ravens' Steve Smith eludes Cincinnati's Reggie Nelson after catching a pass from Joe Flacco in the final minute on Sunday. Smith was penalized for pushing Bengals safety George Iloka during the play, negating the potential winning touchdown. AP Photo/Al Behrman

OPI is among the NFL's 2014 points of emphasis, but the league's new vigilance instructions -- focused on pushing off at the top of the route and downfield blocking before the pass -- don't apply in this case. Smith and Cincinnati Bengals safety George Iloka were coming back toward a long Joe Flacco pass when the contact occurred.

Rule 8, Section 5, Article 2(g) prevents either an offensive or defensive player from "initiating contact with an opponent by shoving or pushing off, thus creating a separation in an attempt to catch a pass" when the ball is in the air.

The replay reveals that Smith -- a 14-year veteran who knows all the tricks -- grabbed Iloka's jersey at the chest with his left hand. With his right arm, Smith pushed away Iloka's left arm. The contact wasn't violent, but Iloka fell to the ground before Smith caught the pass and dashed into the end zone.

Some might believe Iloka would have fallen anyway, with no contact, given his body position. Others have suggested that Iloka flopped or otherwise exaggerated the contact. Neither seems a credible explanation.

We'll never know if Iloka would have fallen, and it doesn't mitigate the fact that Smith initiated contact. Blakeman's crew is the NFL's most conservative and probably not susceptible to a flop. Flopping rather than tackling Smith in that situation wouldn't make much sense for Iloka, knowing the relative unlikelihood that Blakeman would call OPI.

The "controversy" is that you don't often see officiating crews insert themselves into game-deciding plays. The tendencies of Blakeman's crew suggest it is especially likely to "let them play." Smith was no doubt counting on that trend continuing, but based on the wording of the NFL rule, he committed OPI. It was a brutal turn of events for the Ravens and their fans, but the call was more than defensible.

Play: Detroit Lions are called for delay of game, giving them a second chance to kick a game-winning field goal

Referee: Pete Morelli

Analysis: Sunday's game in London demonstrated that even delay of game penalties -- called when the play clock hits :00 before the snap -- aren't nearly as straightforward as they seem.

On several occasions earlier in the game, the Lions appeared to snap the ball after the clock's expiration but were not called for a delay. On place-kicker Matt Prater's errant 43-yard field goal with four seconds remaining, however, they were.

Two important mitigating factors in our understanding of this penalty surfaced.

First, the clock we see on television graphics is not official and might be out of sync with the actual stadium clock. Second, standard officiating mechanics call for the back judge to watch the play clock and -- only after it expires -- look to see if the ball has been snapped. In theory, this mechanic gives the offense a bit more time and prevents the kind of bang-bang call we saw Sunday.

Technically, Prater's misfire never occurred because the penalty wiped out the play. If there were no penalty, the Atlanta Falcons would have won. The Lions had no timeouts remaining, but there was no 10-second runoff because the clock hadn't been running. (Quarterback Matthew Stafford had spiked the ball on the previous play.) The delay pushed the Lions back five yards, and Prater drilled the ensuing 48-yard game winner.

The question is whether back judge Dale Shaw was too aggressive in seeing a delay. Prior to this game, Morelli's crew had called three delay of game penalties in 2014, about midway through the range of this call among the NFL's 17 crews. (The high was eight, and the low was one.)

Though that is a relatively small sample, it's enough to believe Morelli and Shaw are not particularly flag-happy on this mechanic. We can't see the official game clock in the replay, so in this case we have to trust that Shaw followed mechanics and saw what he called.

Play: Roughing the passer on Arizona Cardinals defensive back Tyrann Mathieu

Referee: Walt Anderson

Analysis: In the second quarter, Philadelphia Eagles quarterback Nick Foles scrambled out of the pocket toward his right. A yard before reaching the sideline, he threw a 25-yard completion to receiver Riley Cooper to convert a third down. Anderson then penalized Mathieu 15 yards for a late hit on Foles.

Rule 12, Section 2, Article 9(a) provides guidelines for this penalty. It requires a call if "a pass rusher clearly should have known that the ball had left the passer's hands before contact was made." It adds: "Once a pass has been released by a passer, a rushing defender may make contact with the passer only up through the rusher's first step after such release (prior to the second step hitting the ground); thereafter the rusher must be making an attempt to avoid contact and must not continue to 'drive through' or otherwise forcibly contact the passer."

Finally, the rule states that "incidental or inadvertent contact by a player who is easing up ... will not be considered significant."

When you examine the replay in slow motion, you see that Mathieu completed a step toward Foles either simultaneously with the release of the ball or close to it. At the conclusion of his next step, Mathieu began shifting to an upright posture as if he were slowing down. His right arm/shoulder made modest contact with Foles' chest, sending the quarterback to the ground. Anderson, who was standing behind Foles and thus had an obstructed view at best of Mathieu's steps, immediately threw his flag.

By now, we all understand the NFL's desire to protect quarterbacks from injury. This play, however, stretches the deepest boundaries of their codified attempts. An argument could be made that Mathieu took his one legal step before contact, that he eased up before the collision and that the hit was not significant. It's true that Foles landed on his back, but that was largely because he left his feet to make the throw and hadn't regained full balance upon landing.

In Anderson's defense, this analysis required a slow-motion view of the play that he never saw. The penalty is not reviewable. Finally, Mathieu did extend his arm slightly, an argument against "incidental" contact.

Anderson entered Week 8 with four roughing the passer penalties, tied for third-most in the NFL. That's an active pace. In the end, his call stretched the definition and intent of this rule.