FOXBOROUGH – We should have known.

When the Patriots play the Ravens, weird things always happen.

The Sterling Moore pass defense in the end zone at Gillette in 2011, followed by Billy Cundiff's wide left chip shot.

The "missed" field goal in Baltimore that the replacement refs ruled good to give the Ravens the win a year later. And then Ray Lewis and his mates getting revenge in the playoffs a few months after that… in Foxborough again.

Ray Rice going nearly the length of the field for a touchdown on the game's first play in 2009.

Go back to 2007, when New England was undefeated, but trailing in Baltimore. A Russ Hochstein penalty that actually was to the Patriots' benefit, a "phantom" timeout by the Ravens' bench, and a juggling TD catch by Jabar Gaffney in a Patriots win.

We should have known this latest Ravens-Patriots encounter would be marked by something unusual.

But where to begin?!

The Patriots coming back not once, but twice, from 14-point deficits?

Julian Edelman throwing a TD pass to fellow wideout Danny Amendola?

Rob Gronkowski playing safety on a last-second Hail Mary?

Questionable penalty calls by the refs, a game-sealing INT that turned out not to be because the Patriots couldn't run out the clock by kneeling and had to punt?

Yes, any of those would qualify, but surely the strangest sequence of plays came in the third quarter, when head coach Bill Belichick and offensive coordinator Josh McDaniels trotted out THE most creative half-time adjustment ever.

A player declaring himself INELIGIBLE!

Follow me here…

Rookie center Bryan Stork had injured his right knee in the second quarter, forcing right guard Ryan Wendell to shift over and play that position, while Josh Kline came in and spelled Wendell at guard.

That matchup was being exploited by Baltimore's front seven, and QB Tom Brady was being pressured.

So, down 14 points in the early second half, the Patriots come onto the field with just four o-linemen (Kline stayed on the sideline), while running back Shane Vereen and tight end Michael Hoomanawanui, on consecutive plays, would approach the officials and declare themselves ineligible. In effect, they were the fifth offensive lineman.

The ref then opened his mic and announced to the world, "Number [34 or 47] is ineligible… Do not guard [him]."

Baltimore's defenders and coaches were nonplussed.

What in the name of Vince Lombardi was New England doing? Was it even allowable?

Apparently so.

The idea behind it, it would seem, would be to confuse Baltimore's D and open up passing lanes for Brady and his receivers. By choosing not to cover the ineligible Vereen (or Hooman), the Ravens would seem to have an extra man advantage on D, but instead, they chose to keep a defender in the area… but they weren't sure this was the right reaction.

Brady completed 7-of-9 pass attempts on the drive, the last being a 5-yard touchdown to Gronkowski. He made it look easy thanks to the o-line ploy. Suddenly, Gillette Stadium was rocking (the press box actually was shaking) and New England regained momentum in the game.

None of the players afterward would admit if the adjustment was made on the fly during halftime or if the coaching staff had the idea and worked on it in practice (most likely the latter, given how effective if was). In either event, it was perhaps the greatest coaching tactic, wrinkle – whatever you want to call it – ever employed.

"Nobody's ever seen that before," Ravens head coach John Harbaugh insisted in his postgame comments.

Harbaugh was incensed on the sideline… so much so that he ventured onto the field to voice his displeasure to the officiating crew, which flagged him 15 yards for unsportsmanlike conduct.

"We wanted an opportunity to be able to ID who the eligible players were," Harbaugh continued to explain, "because what they were doing was they would announce the eligible player and then time was taken and they would go over and snap the ball before we even had the chance to figure out who was lined up where, and that was the deception part of it. And that was where it was clearly deception.

"That's why I had to go and take the penalty, to get their attention so that they would understand what was going on because they didn't understand what was going on. And they said that that was the right thing, that they'd give us the chance to ID the eligible receivers so we could actually get them covered. That's why guys were open, because we didn't ID where the eligible receivers were at. So, that's the nature of that particular thing they were doing, that's what made it so difficult."

Harbaugh would not comment, however, on whether he thought the move was "cheap or dirty."

What it was… was just the latest surreal chapter in what continues to be one of the most bizarrely entertaining rivalries in pro football.

We should have seen it coming, shouldn't we?