Playbooks

Single Mug is a defensive set inside the Dime formation, and that changes how you have to think about it. The play list here is entirely coverage and pressure based: Bracket Switch Willie, Cover 1 Hole, DB Blitz Tex 3, 1 LB Dog, Cover 1 Games, Blitz Tex 3, Cov 3 Buzz Show 1, Cover 1 Robber Press, Dime Blitz 2, Double Bracket, Cover 4 Palms, Cover 2 Man, Dbl Safety Blitz, Tampa 2, and DB Blitz. The personnel is Dime 4-1-6, meaning four down linemen, a single linebacker, and six defensive backs, which is the lightest box you can field without going to Quarter or Dollar looks. The "Mug" tag comes from the alignment: the lone linebacker sugars up in the A gap over the ball, giving the offense a pressure read that may or may not come.
What separates Single Mug from base Dime alignments is that A gap presence. With one linebacker mugged over center, the offensive line has to account for an interior rusher pre-snap, which freezes slide protection and often forces the center to set to the mug instead of helping on your best pass rusher. That is where the RLE, RRE, and RDT tags matter: you can rotate your fastest edge and interior pass rushers into this set so the four man rush wins one on one while six defensive backs flood the field behind it. The SUBLB and SLCB tags let you get your most athletic coverage linebacker and your slot corner on the field at the same time, which is how you erase tight ends and slot receivers instead of asking a strong safety to survive out there.
Offensively speaking, this set does not exist. If you are facing Single Mug, you are looking at a defense built to shut down empty, 10 personnel, and four verticals concepts on third and long. If you are running it, the six defensive backs give you Bracket Switch Willie and Double Bracket to double a single elite target while playing man everywhere else, and the DB Blitz family lets you send slot pressure from a leverage the tackle cannot see. Cover 4 Palms and Tampa 2 sit in the same set as Cover 1 Robber Press, so you can show identical alignment and run completely different coverage shells from snap to snap.
Live in this set on third and seven or longer and on any two minute drive where the offense has to throw. That is when the light box costs you nothing and the six defensive backs cost the offense everything.
Read the offensive formation before you commit. If you see 11 or 12 personnel with a fullback or a second tight end, audible out of Single Mug entirely instead of trying to survive the run fit with one linebacker.
Use the mug look as a lie. Show the A gap pressure, then run Cover 1 Hole or Cov 3 Buzz Show 1 so the linebacker drops into the throwing window the quarterback just committed to.
Rotate your RLE, RRE, and RDT tagged rushers in before the drive. A four man rush is the whole plan on the coverage calls, so speed rushers on the edge and a penetrating interior tackle are non negotiable.
User the deep middle on Cover 1 Robber Press and Cover 2 Man so you can jump the seam and the dig, and let the SLCB handle the slot underneath instead of manually chasing shallow crossers.