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Former Kansas City Chiefs head coach Romeo Crennel is the best fit to lead the New Orleans Saints' switch to a 3-4 defense. According to NFL.com's Dan Hanzus, Crennel is a front-runner for the vacant defensive coordinator post, along with Rob Ryan.

Crennel is the smarter choice because the Saints are about to embark on a major schematic shift. They haven't played the 3-4 since the days of the vaunted "Dome Patrol."

That means they have spent several seasons stockpiling 4-3 personnel. However, as big as the transition is likely to be, the Saints need it to happen fast after missing the playoffs in 2012.

Crennel quickly turned a floundering Chiefs defense into an accomplished 3-4 unit in 2010. Kansas City had experimented with hybrid fronts in 2009 with very little success.

Crennel wasted no time slotting 4-3 players like Tyson Jackson and Glenn Dorsey into a true 3-4 front. It's no small wonder, considering his wealth of experience with the 3-4.

Dating as far back as his days as an assistant with the New York Giants, Crennel has worked with 3-4 coaches and personnel. Most important, his expertise was honed coaching the defensive line.

With the Giants, Crennel coached a defensive line featuring the likes of Leonard Marshall, Jim Burt and Erik Howard. His skill teaching a three-man line will be invaluable to the Saints.

The line is where the transition between schemes is most difficult. That's thanks to the fundamental differences between the attacking, 1-gap techniques of the 4-3 and the 2-gap style of the 3-4.

Crennel should be able to quickly mould a three-man line, adept in the style the new scheme demands. That will make the rest of the transition easier.

The other reason why Crennel makes sense for the Saints is the mentality of his defenses. While it's true that the 2-gap, 3-4 Crennel favors is more read and react by nature, that's precisely what the Saints need.

Read-and-react schemes aren't particularly popular anymore. However, it's just as true that the blitz is not a cure-all for every defensive ill. The Saints have found this out to their cost under both Gregg Williams and Steve Spagnuolo.

Crennel's more disciplined schemes could be the perfect tonic in a division featuring Matt Ryan and Cam Newton. In particular, Crennel's knowledge of coverage schemes could be a massive boost to a pass defense that ranked 31st in 2012.

Crennel always builds a strong secondary. His defensive backfields operate a quarter-quarter-half scheme, or cover-8 concept.

It's a scheme that allows corners to mix press techniques with zone instincts. Deep safeties help take away the long pass.

This system helped the likes of Brandon Flowers and Eric Berry flourish in Kansas City. When Crennel was with the New England Patriots, Ty Law, Asante Samuel and Rodney Harrison were the beneficiaries.

Crennel is the right fit for the defense the Saints need now. If Sean Payton wants a quick transition, he shouldn't waste time hiring Crennel.