The Chiefs have had a very impressive run, as winning 11 straight games in the NFL should never be overlooked, but they just haven't faced a team like the Patriots in that span. Also, New England matches up well against Kansas City in a number of areas. New England can stop the run with the best in the league, and Kansas City's defense can't do much if it isn't forcing turnovers, and the Patriots are stingy with the ball.
This isn't to say it will be an easy win for the Patriots, as the game isn't played on paper, but after taking a deeper look into the Chiefs' season, the Patriots likely only will lose if they beat themselves.