KANSAS CITY, Mo. (AP) -- Marcus Cooper may be the embodiment of the unbeaten Kansas City Chiefs.
He played wide receiver most of his career at Rutgers and was drafted by the San Francisco 49ers with the 252nd overall pick, two shy of being Mr. Irrelevant. Cooper caught the eye of Chiefs general manager John Dorsey during training camp, shortly before he was cut by the 49ers.
Dorsey picked the youngster off the scrap heap and turned him over to Andy Reid. His college resume notwithstanding, the rookie wound up at cornerback.
On Sunday, it was Cooper who recovered a fumble for a touchdown, and then picked off a pass that helped boost the Chiefs to a 26-17 win over the Tennessee Titans. The victory left the Chiefs (5-0) as one of three remaining unbeaten teams in the NFL.
"It's a blessing," Cooper said. "I'm lucky to be out there."
Maybe "lucky" isn't the right word. "Surprising" might be a better fit, both for Cooper and the Chiefs, who on Sunday became the first team in NFL history to win its first five games after winning two or fewer the previous season.
"It feels like a dream, but this is reality," said wide receiver Dexter McCluster, one of the holdovers from last year. "It feels good. We put in so much work throughout the week as far as on the field and off the field, and just to see it show on the field, it's just a great feeling."
The Chiefs made some splashy moves in the offseason to turn over a roster that had talented players but far too many holes. They traded with San Francisco for quarterback Alex Smith, who has stabilized the most critical position on the field, and used their No. 1 overall draft pick on right tackle Eric Fisher, who has shown signs of progress when he's been healthy.
But more than anything else, it's been the middle-of-the-road acquisitions that have allowed the Chiefs to rise to the top of the AFC West, where they're tied with the Denver Broncos.
Cooper was picked up off waivers. So was tight end Sean McGrath, who had four catches for 54 yards on Sunday and has helped the Chiefs overcome a litany of injuries at his position.
Donnie Avery has been a productive wide receiver in the NFL, but hardly a star. He signed as a free agent and was perhaps the biggest reason the Chiefs beat the Eagles a couple weeks ago. He also had three more catches for a game-high 91 yards in the win over the Titans.
Fullback Anthony Sherman, playing the most unglamorous of positions, has paved the way for Pro Bowl running back Jamaal Charles, and even caught a pair of passes on Sunday. Guys such as Chad Hall, Junior Hemingway and Quintin Demps have also provided big plays.
"Nobody expected us to be 5-0. We surprised ourselves as well," Charles said. "I'm just glad that we continue to come out here and play games and win."
It's not as if the Chiefs have been perfect. Far from it.
Reid pointed out that the Chiefs beat Tennessee despite going 1 for 4 in the red zone on Sunday, and an offense that has had fits and starts was just 1 of 12 on third-down conversions.
"You can't make a living doing that, right?" Reid said Monday. "You have to make sure you're more efficient on third down, and you have to shorten the third downs a little bit, too."
Still, the Chiefs overcame those obstacles to improve to 5-0 for just the second time in franchise history, and now get the rival Oakland Raiders on Sunday at Arrowhead Stadium.
"Listen, were 5-0 and we're not ashamed of that," Reid said. "But we also know that we got a ton of room to improve. It's important that we continue to do that."
Notes: Avery has a bruised shoulder and will be evaluated this week. ... Fisher is still recovering from a concussion. ... Pro Bowl LB Justin Houston took "a shot to the neck and head and everything else there," Reid said. "He seems to be OK." ... TEs Anthony Fasano (ankle) and Travis Kelce (knee) are still dealing with injuries. "Making progress," Reid said.