KANSAS CITY, Mo. (AP) - It was a gamble from the get-go, the decision by the Kansas City Chiefs to trade two draft picks for Alex Smith this past offseason. So far, it's paying off.

Smith is off to the best start of his career, leading the Chiefs to a 4-0 mark. He's on pace to set career bests for yards passing, yards rushing and touchdown passes, and has even outplayed the 49ers' Colin Kaepernick - the guy who took his starting job last season.

Perhaps most importantly, Smith hasn't made many mistakes. He threw his first two picks last Sunday against the Giants, but has otherwise been flawless. And that's a big reason the Chiefs are tied with the Titans, their opponent Sunday, for the NFL's best turnover margin.