McClain signed a one-year contract after reviving his career with a solid season in 2014. The deal is worth $3 million, with another $1 million in incentives.
The 26-year-old McClain will start at middle linebacker, allowing the Cowboys to move Sean Lee back to his more natural spot on the weak side. Dallas traded for McClain, who didn't play in 2013, last summer when Lee was lost to a season-ending knee injury.
The former top 10 pick by Oakland was dumped after three disappointing seasons with the Raiders and ended up in Baltimore. He never played for the Ravens, retiring and twice walking away from football before getting traded.
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