The Detroit Lions rebuild just got a little tougher. The player popularly known as 'Megatron,' Calvin Johnson made it official on Tuesday morning, filing retirement papers with the NFL. He retires at 30, one year younger than Barry Sanders when he retired.

In his nine seasons, Johnson quietly established himself as one of the pre-eminent wide receivers in football. His career numbers: 731 catches for 11,691 yards and 83 touchdowns. The glaring figure, he only played in two playoff games, one in 2011 and one in 2014.

ESPN's Trey Wingo tweeted that Johnson is walking away with four years left on his contract and potentially $67 Million in salary.

The Hall of Fame Class of 2021 is shaping up to be quite a class. Peyton Manning, Charles Woodson, (presumably) Marshawn Lynch, and now Johnson.

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