Sean Smith signs with Kansas City Chiefs

Sean Smith flashes brilliance, but suffers from inconsistency. (AP) A trade for Alex Smith and the re-signing of Dwayne Bowe naturally pointed a spotlight on

Sean Smith flashes brilliance, but suffers from inconsistency. (AP)

A trade for Alex Smith and the re-signing of Dwayne Bowe naturally pointed a spotlight on the Kansas City Chiefs' offense. Turns out, their defense might be pretty decent, too.

The Chiefs signed coveted free-agent cornerback Sean Smith to a three-year deal on Thursday, per his agent David Canter, adding him to their secondary just days after picking up Dunta Robinson. Those two veterans and incumbent starter Brandon Flowers to form one of the NFL's better cornerback units, at least on paper.

There's the rub, however, especially when it comes to Smith. The 25-year-old Smith, an imposing 6-foot-3 corner who excels in press coverage, appeared to be one of the better free agents available this offseason -- Peter King ranked him No. 28 overall.

And Smith deserves that standing ... when he plays up to his capabilities. How infrequently that happens, however, has been a frustrating reality thus far in Smith's career.

Last season, for example, he turned in two interceptions while covering Larry Fitzgerald during an early-season game but finished the year ranked just 52nd among cornerbacks in coverage, according to Pro Football Focus.

The best news for Smith may be that Flowers ought to take some of the heat off him. Flowers ranked 9th in those PFF metrics in 2012 and has proven himself capable o the No. 1 CB spot.

The abilities of both Smith and Flowers to play one-on-one could free up the Chiefs' safeties -- Eric Berry and possibly Robinson, who either will defend the slot of slide to a free safety role next season.

Grade: B-plus. Smith reportedly will receive an average of $6 million over his three-season contract. That's a respectable price tag on both sides, slightly above what Chris Houston and Derek Cox received Wednesday. While that all would help set the cornerback market, it also would put Smith in decent company.