With the Eagles hosting the Falcons in the 2018 season opener and NBC broadcasting, Cris Collinsworth is bound to be talking about RPOs again. Here’s a guide that was originally published in February during Philadelphia’s Super Bowl run.

Super Bowl 52 marked the final “we’ve arrived” for run/pass options, the packaged play-calls that have been common in college and high school for years.

While NBC’s Cris Collinsworth didn’t seem terribly clear on what exactly is an RPO — they necessarily involve true run blocking, and aren’t just play-action calls — they were an important component of the Eagles’ strategy. These playoffs cemented RPOs as neither a college nor pro thing, but a football thing.

Still, there are major differences between how RPOs look in the college and pro games. In college, a forward pass beyond the line of scrimmage is illegal if any offensive linemen are more than 3 yards down the field. In the NFL, it’s a flag if a lineman is more than 1 yard downfield. That rule difference alone has a considerable impact, as college defensive coaches often point out.

Here’s a primer into some main differences between how these plays are used at each.

1. The NFL doesn’t run many RPOs on downhill run concepts.

The whole idea is the defense can’t know whether the play will be a run or a pass because only the quarterback knows. On every RPO, the line has to block as if it could be a running or passing play.

That can be difficult to navigate on run schemes like power or inside zone. Those plays are all about shoving defenders down the field with double teams or quickly releasing linemen up to the linebackers.

College linemen only have to make sure they don’t get more than 3 yards downfield. The QB has to be careful to make a read and get the ball out quickly, so he doesn’t put his linemen in an impossible situation. For NFL teams, the 1-yard rule makes these concepts nearly impossible to pull off without risking a flag.

Consequently, you don’t see many NFL RPOs that combine the threat of a quick-hitting inside run. Here’s Philadelphia using play-action to run a bubble screen and still nearly committing a penalty ...

... whereas the smashmouth spread offense at the college level is predicated on combining a pass option with downhill, lead run plays:

Even though there’s a chance the QB will throw a hitch route if he sees the right coverage, his linemen are freed up by the rules to attack.

Instead, NFL RPOs rely on run concepts that aren’t designed to send linemen vertical. In particular, the NFL likes the outside-zone play and various sweeps that rely on pin blocks and OL pulling outside, movements that should buy time for the QB to punish aggressive defenders with quick-hitting passes.

Even on this sweep option, Nick Foles is forced to double-clutch before throwing the ball. That results in center Jason Kelce, who’s pulling to block for the sweep, getting too far downfield by the time Foles releases the ball. The Eagles are fortunate not to get flagged.

There’s no margin for error in the NFL and a high risk of either committing a penalty or forcing a throw off a bad read. So their RPOs are designed to be quick and generally only include hitch routes, slants, and outside runs.

2. College RPOs make greater use of vertical routes.

They take longer to develop than RPO routes in the NFL, but that’s another benefit of linemen getting 3 yards of downfield real estate.

One of the most popular and devastating RPOs is the glance route off a downhill run. Alabama blew the title game open against Georgia by punishing late safeties with it.

Backside routes attached to runs are generally the missing ingredient to a complete RPO attack.

The challenge for a spread offense that wants to run is controlling the extra man the defense can drop into the box. If an offense can’t throw the bubble screen, it has to worry about the nickel cornerback or Sam linebacker coming off the edge to stuff runs. So the screen is a constraint:

If they can force the nickel (N, above) to cover down on the slot receiver (Y), the next concern is that free safety (F), who could slip down into the box and serve as the extra man the offense can’t account for with a blocker. The best way to control him is with a route to that X receiver isolated against the cornerback.

There’s a much higher degree of difficulty in executing these throws, which would make them appealing to the NFL, except that it becomes nearly impossible to execute them safely without breaking the professional game’s 1-yard rule.

3. NFL teams don’t use the QB as a runner like college teams do.

The typical counter to RPOs, particularly in the NFL, is to play man coverage. The RPO is built around creating conflict for defenders on whether to play their run fits or their coverage assignments. The QB then punishes indecision or an aggressive run fit with the quick pass. Man coverage erases that conflict by telling the defenders to stick to their men and dropping a safety down to ensure they still have enough numbers in the box to stop the run.

The reason Philadelphia threw fewer RPOs against New England than Collinsworth claimed was the Patriots played a lot of man coverage. Normally, NFL teams punish man coverage by attacking it with routes designed to free up receivers, such as mesh, switch routes, and wheel routes.

College teams often have a simpler way to punish good man coverage that requires less skill and chemistry: They just run the QB.

College teams love to mess up a linebacker’s reads. Gaining a numbers advantage by deploying QB run schemes and giving him an RPO is perhaps the deadliest way to do it.

This play combines almost every facet of the college RPO game you don’t see in the NFL. Boise State is executing a downhill power run play, with the QB reading the middle linebacker to see if he stays home (in which case he throws the bubble to the motioning RB) or if he chases the RB (in which case the QB keeps the ball and runs on the counter play).

The Eagles often made good use of this when Carson Wentz was taking snaps. Then Wentz got hurt, which shows why NFL teams don’t like to rely on QB runs.

“The biggest concern with RPOs is the quarterback getting hit,” Oklahoma State OC Mike Yurcich says. “After all, part of the deal here is that they are blocking as if it’s a run play; they are not protecting the passer. [ESPN’s] Jon Gruden calls it ‘Ridiculous Pass-protection Offense,’ and I understand what he’s saying. We’ve got to get to where it’s sound, so we feel the quarterback can make a read, and if he’s correct in what he sees, then he shouldn’t take a hit.”

In the NFL, RPOs are a nice addition to a pro-style offense that can help force man coverage or bring better angles and numbers for the run game.

Without rule changes, they won’t be more than a way to give the QB a fast option to punish an aggressive run defense.

In the college game, they can serve as the main focus of an entire playbook, the same way the triple option did.