KANSAS CITY, Mo. -- Pump the brakes a bit on the whole Drew Lock-Patrick Mahomes rivalry in the making as the Denver Broncos' hopes of a .500 finish were formally swept away Sunday by a snowstorm and the Chiefs’ offense in a 23-3 Kansas City win at Arrowhead Stadium.

The loss means the Broncos haven't defeated the Chiefs since Peyton Manning retired. Sunday's loss was Denver's ninth in a row to Kansas City, guaranteeing the Broncos (5-9) will finish below .500 for the third consecutive season.

The homecoming for Lock -- who is from Lee’s Summit, Missouri, which is about 13 miles from Arrowhead -- was a difficult one, as the Broncos' offense never found its traction on a snow-swept afternoon. Lock was battered by the Chiefs' pass rush and even with some late completions finished 18 of 40 passing for 208 yards with an interception as the Broncos were held without a touchdown for the second time this season.

The Chiefs had no difficulty against an injury-ravaged Broncos' defense, as Mahomes had 210 yards passing with a touchdown by halftime and finished 27-for-34 for 340 yards, two touchdowns and one interception.

Troubling trend: For over four decades if the schedule says "Arrowhead" in December, football misery has been the result for the Broncos. With Sunday's loss the Broncos are 3-15 in December games at Arrowhead Stadium. The Broncos were 1-6 in December games John Elway started there and 0-2 in December games Jake Plummer started there.

Biggest hole in the game plan: Hey, the Broncos certainly aren't alone, but they still don’t have an answer in coverage for Tyreek Hill or Travis Kelce.

With his 41-yard touchdown catch Sunday, the first of his two touchdowns in the game, Hill had a 41-yard scoring catch in each of the two meetings with the Broncos this season. Hill's second touchdown came with safety Will Parks, who is playing with a cast on his hand, in tow.

And Kelce apparently had tire chains when everybody else didn't. He had 120 yards receiving before the third quarter was half over and finished with 11 receptions for 142 yards. The Broncos tried both linebackers and safeties on Kelce with little success, but like their efforts with Hill, the poor field conditions consistently favored the Chiefs' two biggest receiving threats.

QB breakdown: In some ways, a 309-yard, three-touchdown day in Houston perhaps made people forget Lock is a rookie who had spent 10 full regular-season practices on the field before he made his first start Dec. 1 against the Chargers. He's a player who has many more games to play before it can decided if he is, or isn't, the long-term answer at quarterback.

On Sunday, Lock faced a snowstorm, a Chiefs defense that was far more aggressive coming after him than either the Chargers or Texans, and poor field position for much of the day. The result was a bumpy ride on the learning curve.