Playbooks
Curl Flats out of Singleback U Off Close is a classic zone beater built around a high low stretch on the outside linebacker or flat defender. The concept pairs curl routes from the receivers and tight ends with flat routes from the backfield or slot, forcing defenders in the underneath zones to choose between the sit down curl and the shallow flat. This is not a play action or RPO look, it is a straight dropback pass, and the primary read progression starts with the curl to flat combo on the strong side before working back to the backside curl if the initial flood is covered.
Pre snap, check if the linebackers are showing a hook zone drop depth of five to seven yards, that tells you Cover 3 or Cover 4 and the curl will have a natural window behind them. Watch the flat defender, whether it is a corner, safety, or linebacker, if he widens fast to the flat route pre snap that is a blitz or man coverage tell and you should look to hot route the curl into a quicker breaking route. Post snap, key any user controlled defender sitting in the shallow flat zone or lurking in the curl window, since a smart user can rob this concept by sinking into the throwing lane and jumping the curl route. This play struggles against Cover 2 man and press man coverage on the outside because the flood side gets clogged, if you see hard press corners with a single high safety rotate to a different concept or use motion to check the coverage. Watch for nano blitzes or delayed linebacker pressure up the middle, since the quarterback needs a clean pocket to work through the curl to flat progression, and a fast interior rush can force you off your first read before the flood develops.
Identify the coverage shell before the snap by checking safety depth, if you see two high safeties sitting deep this play is money against Cover 2 and Cover 4 because the curl sits right in the soft spot between the corner and the linebacker drop.
Hot route the backside curl into a dig or speed out if you are facing Cover 3 with a hard sink from the flat corner, since the flood concept on one side can get taken away by a cornerback playing outside contain technique.
Use this on second and medium to second and long, the curl flats combo gives you a high percentage completion with the flat route while keeping the curl alive as a chain moving option against zone coverage.
Sequence this play after HB Dive or Inside Zone Split to bait linebackers into run fits, then come back with Curl Flats to attack the vacated flat and curl windows.
Pair Curl Flats with PA Deep Cross or PA Deep Read in the same set so defenders start respecting the deep shots, which opens up the underneath curl flat combo even more against aggressive user defenders jumping routes.