Sunday was a rough day at the office for the Silver and Black.

After entering Sunday's game tied for the AFC West lead, Andy Reid and the Kansas City Chiefs handled business, beating the Oakland Raiders 26-15.

With the loss, the Raiders fall to 6-7 with three games left on the regular season slate.

Here are four, quick observations from Sunday's loss to the Chiefs.

1. Amari Cooper was able to give it a go

After not practicing Wednesday and Thursday, there was naturally speculation about Amari Cooper's availability for Sunday's divisional matchup at Arrowhead Stadium, but No. 89 put that speculation to rest as he trotted out for the first play of the afternoon.

However, his afternoon ended prematurely after he injured his ankle in the second quarter, acting as the lead blocker on a pitch to DeAndre Washington.

In his limited time on the field, Cooper did not record a catch.

2. Bruce Irvin kept rolling

Headed into Sunday's game, Bruce Irvin was in the midst of his most productive stretch of football in 2017, and he kept that positive momentum rolling Week 14 against the Chiefs.

His first quarter sack of Alex Smith, was not only takedown No. 6.5 of 2017 for Irvin, but it also helped squash a Chiefs drive that was picking up steam in a hurry.

The versatile linebacker didn't stop there either, he not only picked up another sack before the first quarter came to a close, finishing his day with a pair of sacks.

Irvin has been a man on a mission the past month or so, and his stellar play is a big reason why the Silver and Black have seen an uptick in sacks as of late.

Khalil Mack deservedly gets a ton of attention along the defensive line, but when Irvin is able to make life difficult for the opposing quarterback, it helps the defensive line as a whole.

3. The Raiders struggled stopping the run

The past two weeks, the Silver and Black had done a much better job at limiting teams on the ground, but alas, Sunday afternoon that wasn't the case.

In the first quarter alone, the Chiefs were able to rack up 55 yards on the ground, and by day's end that number had increased north of 100.

The Chiefs boast one of the more balanced offensive attacks in the NFL, and that balance was on full display Sunday afternoon at Arrowhead Stadium.

Not only was Alex Smith his usual, clinical self, but Kareem Hunt was able to get rolling too, and that typically spells bad news for opposing defenses.

Such was the case for the Raiders on Sunday.

4. Derek Carr just couldn't get rolling

Truthfully, I'm not sure why, but D.C. looked out of sorts Sunday afternoon at Arrowhead Stadium.

He finished the first half with just 31 passing yards, and ended the game with one touchdown and two interceptions.

Give credit to the Chiefs secondary; although they were without the services of Marcus Peters – the best playmaker in the group – they were still sticky in their coverage all day, and their success is a big reason why the Chiefs took care of business against the Silver and Black.

When he's firing on all cylinders, Derek Carr is one of the premier quarterbacks in the game, but unfortunately Sunday was just not one of those days.