In their AFC Divisional round game against the Ravens, the Patriots ran, a set with four offensive linemen.

They came out with six players normally considered eligible receivers, even though you're only allowed five. Shane Vereen had declared himself ineligible, but was lined up as a slot receiver. In the confusion of a rare "player declaring himself ineligible" announcement, CJ Mosely is jogging over to line up over Vereen. Meanwhile, nobody guards Michael Hoomanawanui, a tight end lined up where the left tackle normally is, and he makes a catch for a nice gain.

The play caught a lot of people's attention because Ravens coach John Harbaugh felt officials didn't give his team enough time to adjust to it, even though that's not a thing the rulebook asks refs to do.

Most of the time, a trick play is just that -- a trick, something a team runs once, hoping to catch the opponent by surprise. However, I think New England's four OL set is something I could see them running routinely, not just as a gimmick, but as a legit football strategy. Here's why:

Tom Brady completed 22 of 22 passes for 209 yards and 3 TDs when he unloaded the ball within 2 seconds of the snap vs. the Ravens. Insane. — Jeff Howe (@jeffphowe) January 12, 2015

When Tom Brady decided to hit his first read against the Ravens, he was literally perfect. Baltimore's defense was 0-for-22 at finding a way to break up his passes. Brady had no miscommunications with receivers. All 22 throws were accurate enough that Brady's receivers could catch them. And Brady's receivers didn't drop a single pass. Sure, there were probably some occasions where Brady's first read was guarded closely and he wasn't able to throw in the first two seconds, but every time he pulled the trigger, it worked. That's incredible, and it's telling.

When Tom Brady decided to hit his first read against the Ravens, he was literally perfect.

Trick plays always have disadvantages. For example, on the double pass Julian Edelman ran last week, a) there's essentially just one live passing route to defend b) the person passing the ball doesn't have an offensive line in front of him, and of course, c) the person throwing the ball is a wide receiver. Sure, Edelman played quarterback in college, but he's been an NFL wide receiver for a while. He doesn't have the arm strength, accuracy, or perhaps most importantly, experience making decisions against NFL defenses that NFL quarterbacks have. The trick play leads to an easy TD when the defense isn't prepared, but if the defense is prepared, there's a high likelihood of an incompletion -- or worse, a sack for a big loss or an interception.

With the four OL play, the obvious disadvantage is that there are only four offensive linemen, with a tight end lined up as the "fifth" offensive lineman. That means there's less blocking, and that means the defense can get to the quarterback rather quickly.

But with Tom Brady and Tom Brady's receiving corps, how big of a disadvantage is that? He's murderously good at quickly identifying who he's going to throw to, dropping back, and executing. He went 22-for-freakin'-22.

The thing that makes the Pats' success replicable is that it calls for six players with eligible numbers to take the field and one to declare himself ineligible. It doesn't have to be the same person ineligible every time. Let's look again at the starting position from which they ran the pass to Hoomanawanui.

You're required to have seven players on the line of scrimmage on every play, and the two on the ends are the ones who are eligible receivers. In this set, it's Hoomanawanui and the receiver below Vereen. The five in between them are "covered," and therefore ineligible.

Normally, these five are offensive linemen, big hulking players that look like they aren't going to receive a pass. The defense doesn't think much about them, because they don't look like they're ready to receive a pass.

The trickery on the play the Pats ran is that Vereen looks like a running back lined up in the slot when he's really an ineligible "lineman." The Ravens attempt to guard him, not realizing he was ineligible and somebody else was eligible.

By playing six players with eligible numbers, the defense suddenly has to think about who is eligible and who is not. By making very subtle adjustments to who is on the line of scrimmage and who isn't, the Pats could wreak havoc.

If the receiver in the left slot steps up to the line of scrimmage and the receiver below Vereen takes a step back? Suddenly Vereen is eligible, and Hoomanawanui is not. He can play offensive linemen on this play.

If Vereen takes a step back and Rob Gronkowski (right above Vereen) takes a step forward? In this setup, Vereen is eligible and Gronkowski is not. Hoomanawanui would be.

The receiver on the very top of the screen takes a step forward and Vereen steps back? Now Vereen and Gronkowski, but not Hoomanawanui, are eligible.

Imagine an entire drive where the Patriots switch how they line up each play. The defense would see the same personnel and essentially the same formation, but would be prevented with a wide range of different players to guard.

This would be hard to execute -- a slight mess-up could lead to a flag for illegal formation -- but if executed properly, would be incredibly difficult to defend.

As John Harbaugh found out Saturday, it's not the referee's responsibility to ensure the defense knows which receivers are eligible. All the referee has to do is report a player who has changed his eligibility -- in this case, a player lining up in an ineligible spot would have to inform the referee, which Vereen did Saturday. From there, it's the defense's responsibility to identify the five guys who can catch passes.

For a defense to guard against cycling ineligible receivers, they would have to make several identifications before the snap. They'd have to:

Listen to the ref announce which number is ineligible

Find that number

Make sure nobody is guarding that player

Make sure somebody is guarding the player who actually *is* eligible, which is on the other side of the formation

By the way, you also have to guard the other four live passing routes on each play, so just identifying and stopping the one tricky one isn't the end of it.

Trying to defend Tom Brady and company is already hard enough. If they've got you trying to locate jersey numbers before the snap, there's a solid chance you've already lost.

Tom Brady only needs an instant to decide who he's passing to and complete that pass. The confusion caused by fiddling around with the eligible receivers could provide that instant. And that benefit could easily outweigh the negative of only having four offensive linemen blocking.