Applying for the Job
Call the team that you are applying to and say you want to be their defensive line coach. Develop a specialty when you go into the coaching field. To get a job as an NFL assistant coach, you will start off by coaching a position. If you have been a defensive coordinator at the college level, chances are you will start off as a defensive line, linebacker or defensive back coach. You will have to show your expertise in leading one of those groups by demonstrating your knowledge in the interview process.
Write a letter of application and demonstrate your knowledge of your prospective team's personnel. You are not going into the interview to show the head coach and general manager what a nice person you are. They are considering bringing you aboard because of your knowledge and talent. Give them an assessment of the talent on hand and what schemes you would employ to make that talent effective. The coach and general manager want to hear your coaching game plan.
Get a reference or a series of references to vouch for your coaching ability. You won't need a formal letter. However, if you tell the general manager who is thinking of hiring you that coach Joe Jones of State University understands what you can add to the team, coach Jones better call back shortly when the general manager calls him to pick his brain about you. Nothing will end a coaching candidacy faster than providing a false reference.
Develop an overall coaching philosophy and demonstrate it during your job interview. You may not have to be in lock step with your prospective bosses, but they will want to see that you have enough in common that you can work together. They will also want to see that you have thought about the game enough that you have a philosophy. For example, if you are a defensive coach, decide whether you teach your players to blitz and pressure, or if you want your players to lay back and invite the other team make mistakes. There is no right way or wrong way. However, you have to explain why you think your philosophy will work and how you will get your philosophy across to your players.
Talk to other coaches and let them know that you want an NFL coaching position. These coaches are your network. They will make calls on your behalf and find out where the openings are. That way you will apply to the right teams and you won't waste your time.
Hire an agent who specializes in finding coaching jobs. This is different from a player agent. You want someone who is aggressive, but you don't want someone who is obnoxious. A coaching agent is a bit more reserved than a player's agent. Many teams may be pursuing a player, while an assistant coach may not have as many opportunities and therefore must present himself in a more dignified manner.