When and where to run it

Game planPair it with Split Back Lead after defenders begin chasing the first crossing back.
Game planTrail punishes the player who commits to the initial fake and leaves the opposite edge late.
Game planMirror the call for Split Back Left.
Game planIf the edge is capped, turn the trail path north-south underneath the contain defender.
Game planKeep the corner route high enough to pull the opposite deep defender away from the crossing action.

Pre-snap to post-snap

Read the defense

Pair it with Split Back Lead after defenders begin chasing the first crossing back.
Trail punishes the player who commits to the initial fake and leaves the opposite edge late.
If the edge is capped, turn the trail path north-south underneath the contain defender.
Keep the corner route high enough to pull the opposite deep defender away from the crossing action.

Cover 0: Anything that develops slowly — pressure gets home first Better answers: Four Verticals, Mesh, Slant-Flat, Smash
Cover 1: Outside vertical shots — the free safety caps them over the top Better answers: Mesh, Drive, Smash, Y-Cross, Four Verticals, Levels
Cover 2: The flats — the corner squats and jumps anything quick outside Better answers: Smash, Four Verticals, Flood
Tampa 2: The deep middle — the Mike runs it, so a straight seam is contested (unlike base Cover 2) Better answers: Smash, Flood
Cover 3: Deep outside — the three-deep shell caps outside verticals

Troubleshooting

Avoid it when exchange timing is not yet dependable, when the rush closes the delayed mesh immediately, or when outside leverage is sitting untouched on the carrier side.
The live back leaves too early and collides with the fake. Honor the one-count delay before tracing the trail path.
The quarterback chases the mesh. Use a fixed landmark so the delayed carrier knows exactly where the ball will be.
Calling Lead and Trail with different tempos or stances, which lets defenders identify the live back before the snap.