It doesn't matter if the Chiefs run a 3-4 or a 4-3 defense next season because the amount of time spent in sub-packages and the number of positions that need to be addressed in the offseason remain the same anyways.
1. If the Chiefs remain in a 3-4 defense they need to find another defensive end to replace Glenn Dorsey and a SILB to replace Brandon Siler/Jovan Belcher.
2. If the Chiefs switch to a regular 4-3 defense and you have Justin Houston and Tamba Hali as your two defensive ends then you're going to have to find two new LB's to play on either side of Derrick Johnson.
3. If you run a 4-3 under you're going to have to find a 3-tech defensive tackle and another LB.
As you can see, it's two spots that have to be addressed either way -- whether that's the 3-4, 4-3 or the 4-3 under. That's not including the decision on Tyson Jackson and his contract situation with him due just over $14 million next season. Reaching a restructured deal with Jackson would mean that spot can be solidified.
There's also the CB position and perhaps an upgrade at safety that needs to be addressed on the defense either way.
Can the Chiefs count on Jalil Brown, Tysyn Hartman, DeQuan Menzie or Javier Arenas to step in and be the starters at any of these defensive back spots next season? Should that change how they approach free agency?
There are a handful of good CB's that will be free agents next season. Dominique Rodgers-Cromartie, Brent Grimes, Tracy Porter, Quentin Jammer, Pacman Jones, Nate Clements and more. You can see a list of free agent cornerbacks here at spotrac.com.