Below you will find clips of two of LeSean McCoy's three longest runs of the season. The first came against Dallas in the first quarter, a 36-yard run. The second came against Tennessee in the second quarter, a 53-yard run. See if you notice any similarities:

Give them both a couple looks.

How about now:

Yep, those are both unbalanced lines, with Brent Celek lined up at the tackle position and Jason Peters lined up at tight end. As you see in the animated versions, both runs ended up going to the weak side of the formation. In fact, when you look at the six runs of 20+ yards that McCoy has gashed this year, you'll notice something missing from all but one of them: a  safety in the box on the side the play was run to.

Here's the 38-yarder against Dallas from the third quarter:

Highlighted is Cowboys safety Barry Church, lined up on the strong side of the formation. The run ends up going to the weak side.

Here is a 26-yarder against Houston:

Again, the run goes to the weak side.

We mention all of this because the Seahawks are looming, and they happen to feature the best strong safety in the game. I would argue Kam Chancellor is the best player on that defense, period. Two things about Chancellor: he covers much more ground and is much more intuitive than most strong safeties you will watch. While Earl Thomas covers plenty of ground and enables Chancellor to roam, the Seahawks ability to use Chancellor as a roving enforcer is what makes their defense the caliber that it is. Seattle showed last week that it has no fear putting Chancellor on a wide receiver, whether it was Anquan Boldin, Vernon Davis or Brandon Lloyd, either out wide or in the slot.

Go back and watch the first clip from the Dallas game. Notice how Cowboys safety J.J. Wilcox gets sucked inside on the counter step, leaving wide open real estate for McCoy to enjoy.

Chip Kelly knows what fans of the Eagles defense have realized over the last four years: if you can exploit a team's safeties, you can win a lot of football games. The Eagles' early success on the ground last week set up plenty of mismatches for Jordan Matthews, who was routinely open on deep crossing patterns behind the second level of the defense. With the Seahawks, Chancellor is a level all to his own. If you want to watch a game within a game on Sunday, keep an eye on 31 and how the Eagles attempt to avoid him.