In my original post on Split-Safety coverage I outlined a simple system in the 4-2-5 for handling trips formations. The base adjustment is solo. This coverage locks the away side into solo coverage and allows the read side to defend the trips with a variety of options. This is the preferred way to defending the trips side of the formation. However, like any coverage, if you sit in it too long the offense will eventually attack the open side. Solo coverage is most vulnerable to the single receiver side. That is where special coverage comes into play.
Special is designed to create games and options on the single WR side. In this post, I will cover some of the coverage options that can be used have to defend routes to the single WR.
The first and most basic coverage to the open side would be "bracket." This coverage allows the WS to be in a position to aggressively force the ball on the run and take away the quick and intermediate routes of the #1 WR on pass plays.
The corner is man to man soft over #1. His rule is DGBD...Don't get beat deep. He has #1 and he needs to be able to defend the fade, post, corner, and skinny. The WS upon reading pass needs to work into a trail position on the WR. From this position he is man to man on any inside, outside, or stopping route by the WR. The linebacker will have the back man to man.
During the release phase the WS must work into a trail position. Versus a comeback route the WS should be in the proper position to take this route away.
Also, Versus a post, the WS and corner should have the WR on a high-low with no place for the QB to put the football.
Trail Coverage is the reverse of bracket. The corner will align outside and deny any outside releases by the WR. After the initial release the corner will work in a trail position, and is responsible for any quick, intermediate inside/outside cut bt the WR. The WS is soft man over #1 with DGBD responsibility.
This is a great change up and can easily be mistaken for solo coverage. This will be confusing to quarterbacks. Trail coverage on the dig route looks like this.
The final option I will discuss will be simple 1/2's coverage. 1/2's coverages is a great change up on the open side. It changes up the run force to that side, allows the corner to sit and have interception chances, and keeps the backer from having to run with the running back to the flat. The only situation where the the backer would have the back man to man is on a deep release. I am not going to go into too much detail here, there is plenty of discussion and videos on playing halves coverage. Brophy especially has some good resources on running this coverage versus, multiple sets.