Source: Lions, LB Barnes reach 3-year extension

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The Lions and linebacker Derrick Barnes have agreed to a three-year, $25.5 million extension, a source told ESPN's Jeremy Fowler, with $16 million of the deal fully guaranteed at signing.

A key part of Detroit's defense, Barnes was limited to just three games last season after suffering a knee injury in a Week 3 win over the Arizona Cardinals. It was the first time in Barnes' four seasons in the NFL that he failed to play at least 15 games.