UNDATED (AP) — It didn't take Jim Caldwell very long to become an NFL head coach again.

The Detroit Lions say they've hired Caldwell as their new coach and will introduce him at a news conference today. He takes over for Jim Schwartz, who was let go after a second-half collapse led to a 7-9 season.

Caldwell spent this season as Baltimore's offensive coordinator and was head coach of the Indianapolis Colts from 2009-11. He led the Colts to the Super Bowl in his first season but was dismissed following a 2-14 campaign that left him 26-22.

San Diego Chargers assistant and former Arizona Cardinals coach Ken Whisenhunt was seemingly Detroit's top choice. But he chose to take the head coaching job at Tennessee on Monday night.

Meanwhile, Whisenhunt says the one thing he's learned about the NFL is the importance of chemistry, and he decided the Titans were the best fit for his second chance to run a team. The Titans have introduced Whisenhunt as their 17th head coach and only their third since moving to Tennessee.

Whisenhunt's decision prompted the Chargers to elevate Frank Reich from quarterbacks coach to offensive coordinator.

Also in the NFL, the New York Giants have hired Packers quarterbacks coach Ben McAdoo as their offensive coordinator. McAdoo replaces Kevin Gilbride, who retired.

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