KANSAS CITY, Mo. -- San Diego Chargers quarterback Philip Rivers had an interesting observation about why the Kansas City Chiefs have greatly reduced the number of pass plays of 20 yards or more.

"They've certainly pressured but they haven't been as exotic with the pressures as they were last year," Rivers said on a conference call with Kansas City-area reporters. "They still have them and they still show them and we know they like to do all kinds of different things. They never really let you get settled in. They never really give you a pattern of what they like.

"They're a little more not conservative but everything has been a little tighter [in the secondary] and as far as what they've done pressure-wise."

The Chargers and Chiefs play against one another on Sunday in San Diego. Rivers and the Chargers added more than their share of misery to Kansas City's defensive problems last season. Rivers threw for 621 yards in San Diego's two victories over the Chiefs. He completed 10 passes of 20 yards or more against the Chiefs, including a 26-yard touchdown to Seyi Ajirotutu with 24 seconds left to beat the Chiefs 41-38 at Arrowhead Stadium.

To all of their opponents, the Chiefs allowed 63 pass plays of 20 or more yards during the regular season last year and another six in the playoff loss to the Indianapolis Colts.

The Chiefs have allowed 11 such plays this year.

They aren't blitzing quite as much this season. They've sent five or more pass-rushers after the quarterback 41 times in five games, or about eight times a game. They blitzed slightly more than 10 times per game last season.

A bigger difference is in their coverage. It's been much more solid. Cornerback Sean Smith and the safeties are having strong seasons.

"There's not a lot of people running wide open," Rivers said. "Every secondary in the league is giving up some plays but they're really making teams earn it each and every week."