ESPN: Insider Which NFL assistants are next in line to become head coaches? We asked Scouts Inc. to rank the top 10. Every season, several assistant coaches, whether they contribute to the success of a Super Bowl contender or lift the fortunes of a particular unit, emerge as head-coaching candidates. Scouts Inc. identifies the assistants who have distinguished themselves the most this season and who will likely be setting their sights on bigger things in the offseason. 1. Rex Ryan Defensive coordinator, Baltimore Ryan without a doubt is the best defensive coordinator in the NFL. Every defense he has touched has turned to gold. Ryan is an aggressive coach who always keeps offenses off balance with his unique personnel groupings and multiple blitz-pressure packages. He has outstanding communication skills, relates well to players and is very approachable. Ryan has proved he has good player evaluation skills by identifying physically athletic players who best fit his aggressive schemes. On top of that, he understands how to develop team chemistry, which is so critical in building organizational team concepts in the NFL. 2. Ron Rivera Defensive coordinator, Chicago A former NFL player, Rivera understands his players' situations very well, is an excellent communicator and relates to the modern player. The Bears' defense has been among the very best in the league for the past couple of years and Rivera deserves much of the credit for that success. Chicago's defenders play smart, rarely make mental errors and understand their assignments and fits very well. "Tampa 2" defensive coaches are all the rage right now and Rivera understands the scheme as well as anyone. Rivera's name was tossed around for available head-coaching jobs last year and his momentum should only gain steam after another outstanding season. 3. Ken Whisenhunt Offensive coordinator, Pittsburgh Whisenhunt is an up-and-comer who has been instrumental in the development of QB Ben Roethlisberger. Although Whisenhunt looked like a genius a year ago, his offense -- and Roethlisberger -- were not the same in 2006. That isn't necessarily a blemish on Whisenhunt, as he is innovative and very intelligent. He is a fine communicator and a fearless play-caller. The Raiders wanted him as their head coach before they hired Art Shell and Whisenhunt wisely decided to stay with Bill Cowher in Pittsburgh, where he could become the successor. 4. Russ Grimm Assistant head coach/offensive line, Pittsburgh Grimm is respected by coaches and players alike because he is a tough, no-nonsense straight shooter who coaches like he played back in his days as one of the top "Hogs" in Washington. He has a great understanding of offensive line play, keeps things simple and is a fine communicator. Cowher promoted Grimm to assistant head coach this past year as a testament to his abilities. Grimm went to the University of Pittsburgh, is from the area and would be a fine candidate to succeed Cowher for the head job of the Steelers. 5. Cam Cameron Offensive coordinator, San Diego San Diego has the best running back and tight end on the planet, but this outstanding offense has as much to do with Cameron as the exceptional talent base. Cameron has been instrumental in the development of QB Philip Rivers and the transition to Rivers from Drew Brees, which was seamless. The Chargers may have the most-balanced offense in the league and Cameron is exceptional at keeping this group unpredictable. San Diego is an extremely difficult team to prepare for and Cameron is a huge reason why. 6. Clancy Pendergast Defensive coordinator, Arizona Pendergast is an up-and-coming coach who is very innovative in his game plans and designs on a weekly basis. He is an aggressive play-caller who doesn't allow the offense to dictate tempo. He understands the strengths and weaknesses of his defensive personnel and places them in the best positions to make plays. He has very good people skills, relates well to his players and is an outstanding teacher of the game. 7. Mike Tomlin Defensive coordinator, Minnesota In his first year in Minnesota, Tomlin seamlessly instituted a new defensive scheme (Tampa 2) with fine results. This is the scheme in vogue across the NFL right now and this bright young coordinator has quickly made a name for himself. He utilized the talent that was there for him extremely well. Minnesota's defense was extraordinary against the run, generated turnovers with regularity and made a lot of big plays. The Vikings' defense will only get better in his second season as coordinator and Tomlin's star is only getting brighter. 8. Jim Schwartz Defensive coordinator, Tennessee Schwartz has learned under two of the best head coaches in the NFL in Bill Belichick and Jeff Fisher. He is very detail-oriented and well-organized in his game preparation. He loves to pressure with multiple blitz packages and places a lot of pressure on opposing quarterbacks. He relates well to players and has an outstanding work ethic. He is a very smart coach who has a good understanding of the salary cap as it relates to team-building in the NFL. 9. Rob Ryan Defensive coordinator, Oakland Ryan has done an unbelievable job in getting his players to buy into his system. He has learned under Belichick, not to mention his father, Buddy Ryan, one of the best defensive minds in NFL history. Ryan relates extremely well to players and is an outstanding teacher of the game. He has a passion for evaluating and developing players who best fit his system. Without question, both Rob and his twin brother Rex (Baltimore) were born and groomed to become head coaches in the NFL as legacies of the founding father of the 46 defense. 10. Josh McDaniels Offensive coordinator, New England McDaniels is another young coach who is on the fast track to becoming a head coach. Belichick has a tremendous amount of respect for McDaniels' ability to keep defenses off balance with his play-calling. He is a smart, instinctive coach who has a great understanding of the Patriots' system in drafting and developing players. McDaniels is an outstanding evaluator of talent. He has done a great job with QB Tom Brady and is very similar to Jets head coach Eric Mangini in building team chemistry as it relates best to organizational concepts.