This season the New England Patriots have faced a number of mobile quarterbacks. Some were small (Tyrod Taylor), some were big (Ben Roethlisberger), some were Supermen (Cam Newton) and some were Saints (Drew Brees).
Now, in the divisional round of the playoffs, they'll face another in the Tennessee Titans' Marcus Mariota. He doesn't have the same Hall of Fame presence as Brees, but that doesn't mean the Patriots aren't worried.
"He actually knows when to run and when to pass the ball when scrambling," Patriots defensive back Duron Harmon told reporters in trying to explain what separates Mariota from other mobile QBs. "It's a very unique skill because a lot of guys, once they get scrambling, they're not even looking downfield anymore. They're just looking to run. But, he always has his eyes downfield, always knows when to run, when to throw the pass, and I would say his touch on the ball, too, that gets people open when he's scrambling is really good."
Roethlisberger is terrific at keeping his options open, and so is Brees. But that ability, along with a speed (5.9 yards per rushing attempt for his career) few QBs have, is what makes Mariota a serious threat to the Patriots.
No, the Titans won't beat New England. They're not good enough yet. Few teams beat Tom Brady in Foxborough; that'd be like Jim Kirk losing a fistfight on the Enterprise bridge.
Fewer teams beat Brady at home on a Saturday night. Since 2002, as Yahoo's Dan Wetzel writes, the Patriots are 9-0 in home Saturday night playoff games.
No, Mariota won't win.
Considered more of a finesse player at Oregon, Mariota has developed into more of what, traditionally, many would consider an old-fashioned football player. He doesn't throw with great accuracy, and he won't blow you away with passing yardage, but he will fight and scrap.
One scout with whom B/R spoke compared him to Jim Plunkett, the former Raiders quarterback.
Take last weekend, for example, when Mariota threw a pass, had it blocked and had the awareness and athleticism to gather the loose ball in his hands and run it in for the score. It was the first time such a play had happened for a score in postseason history. And it caught the attention of the Patriots.
"I mean, first of all, that's a very, very hard play to make, and that shows you his skill set, his athletic ability," Harmon said. "To be able to throw the ball, have it knocked down and be able to catch it where he caught it and go in and run and score and dive ... it shows his athletic ability. It shows that any time he touches the ball he's dangerous."
The key—and something the Patriots presumably are practicing all week, and diagramming in the classroom—is keeping Mariota in the pocket. That's where he does the least amount of damage. It's when he's on the move, with a multitude of threats to potentially exploit, when he is at his most deadly.
"It's not like if he stays in the pocket he can't make throws," defensive back Devin McCourty told reporters earlier this week. "But when he escapes outside the pocket and he has the ability to run and throw, you honestly really don't have a shot to stop him."
McCourty further explained that Mariota's flexibility will test the Patriots' defensive discipline.
"We've played quarterbacks like this where we do want to try to keep him in the pocket, but I think that's just the beginning part of it," McCourty added. "We also, when we're man coverage or zone coverage, we've got to be able to play our zones or our man tight and not allow windows or not allow a great pocket for him to sit back there and throw because he's a good enough passer that he'll make all the throws on the football field."
In trying to limit their own mistakes, the Patriots excel at forcing opponents into miscues of their own, especially at home. So Mariota will have to throw a clean game Saturday for the Titans to have a chance. But they'll need more.
They'll need a huge rushing day from the physical force that is running back Derrick Henry.
They'll need their defense to somehow slow Brady (good luck with that).
And they'll need Bill Belichick, the best defensive mind in history, to misfire on cooking up some intense scheme to slow Mariota (good luck with that, too).
Get all of that, and who knows? Maybe, just maybe, they can make the Pats worry.
We'll see if Mariota the football player can put that scare into the unbeatable Patriots.
Mike Freeman covers the NFL for Bleacher Report. Follow him on Twitter: @mikefreemanNFL.