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It's been a while since Jim Harbaugh has coached in the NFL, but it may not be much longer until he's back. Harbaugh coached the San Francisco 49ers from 2011 through 2014 before returning to the college ranks to coach at his alma mater, the University of Michigan.

Fresh off a national title, Harbaugh is once again doing the interview rounds with NFL teams. He already completed an interview with the Los Angeles Chargers and another with the Atlanta Falcons, the Las Vegas Raiders are expected to have interest, and there could be several more teams that eventually come calling.

Why is he sought after? His brother, Baltimore Ravens head coach John Harbaugh, thinks he knows. And he explained why to ESPN during an appearance on The Adam Schefter Podcast

"He may be the best team builder in football right now," the elder Harbaugh said of his younger brother. "Nobody builds a team better. He knows how to put it together, top to bottom."

Harbaugh's San Francisco teams started off very well, going 13-3, 11-4-1, and 12-4 in his first three seasons, one of which ended in a Super Bowl loss to John's Ravens. The Niners went just 8-8 in Harbaugh's final season, though, and reports at the time indicated that his coaching style began to rub some the wrong way. He is well-known as a tough-minded coach, and that has translated to success, if not always perfectly harmonic relationships. 

Whichever team -- if any -- hires Harbaugh will know what it is getting into, and presumably will give him as many resources as are necessary for him to find success early and often. Maintaining that success over the long term is a different challenge, and one that both the team and Harbaugh will have to navigate when it comes.