In recent years we've seen more and more teams converting to the 3-4 defense. There are now three AFC West teams running the 3-4 defense and with the Bills making the conversion this season, all the AFC East teams are. It's become popular in recent years and that's not necessarily a good thing for the Chiefs.
What defines many 3-4 defenses is the nose tackle. The problem is that there's very, very few competent nose tackles in the NFL.
ESPN's John Clayton suggests that the more 3-4 teams we see, the less quality we'll see.
"I honestly think that too many teams are making the switch to the 3-4 and that there aren't enough good nose tackles or five-technique defensive ends to make the 3-4 work well," Clayton wrote on ESPN.com.
The Chiefs appear to have the defensive ends down with three players drafted in the last two seasons at the position but nose tackle could be a big problem quickly. Ron Edwards is no spring chicken and didn't dominate the nose tackle position last season.
After that, the Chiefs don't have anyone on the roster capable of playing that role and now, with more teams looking for similar players, it's going to be difficult to find.