The team announced Nico Marley -- an undrafted free agent LB out of Tulane -- has officially inked a deal with them after he impressed coaches at the team's rookie mini-camp.

What's REALLY impressive ... Nico is pretty undersized as far as NFL linebackers go ... he's only 5'8". (For the record, Bob was only 5'7")

Of course, this doesn't mean Nico will be with the team on opening day -- he still has to earn a roster spot ... but still, it's a great start.

Athletes seem to run in the family ... Nico's dad, Rohan Marley, played college football for Miami back in the day (with The Rock and Ray Lewis!) before a stint in the Canadian Football League.

Nico tweeted about the signing -- "My family and I are extremely grateful to the Washington Redskins organization ... for giving me this opportunity to prove myself in mini-camp."

"All I've ever needed was a chance to prove myself. Been hearing I'm 'too small' my whole life and that won't ever stop me."