KANSAS CITY, Mo. _ The sport of baseball is an unpredictable beast, a nightly escapade relying of the random nature of balls in the air and fallible men playing a children's game. No man should ever try to earn a fortune by wagering on the results of this game. But for close to four seasons, the Kansas City Royals' defense has been a pretty safe bet.

For four years, the unit has made spectacular plays and rationed its errors and covered vast ground in the outfield. For two days here at Kauffman Stadium, that same defense suffered through an uncharacteristic slump.

The latest breakdown came in an 11-3 loss to the St. Louis Cardinals on Monday night. The latest frustrating sequence came as an army of red invaded a ballpark on the first night of a four-game I-70 series.

The number of Cardinals fans did not eclipse the home fans on a cool evening in Kansas City, yet the proliferation of red did lead to some strange sounds during a fourth-inning debacle in which Royals starter Ian Kennedy struggled to throw strikes and shortstop Alcides Escobar and catcher Drew Butera made costly errors. By the end of the inning, the Cardinals had put up six runs, and the Kansas City defense had malfunctioned again. The Royals (57-54) will look to even the series here on Tuesday night before heading across the state of Missouri on Wednesday.

On Sunday afternoon, the Royals gifted the Seattle Mariners four runs during a gaffe-filled second inning, botching a rundown and extending the pain after a passed ball from Butera. The mistakes resulted in a loss before the Royals regrouped to claim the second game of a doubleheader.

On Monday, the porous defense surfaced in the top of the fourth inning and included the following:

1. With the game tied at 1-1, Kennedy loaded the bases by yielding a single, double and a walk. He responded by inducing a well-struck grounder just to the left of shortstop Escobar.

The pace of the grounder made for an easy double-play ball. Yet Escobar booted the grounder, allowing a run to score and the bases to remain loaded.

2. Kennedy followed by striking out the Cardinals' Randal Grichuk before issuing a bases-loaded walk to Greg Garcia, which had little to do with the defense but did illustrate Kennedy's command issues.

In six innings, he walked four while allowing six hits and seven runs (six earned).

3. Moments later, Butera attempted to throw behind St. Louis' Dexter Fowler at third base. But the baseball hit Fowler in the back and skipped into left field, allowing the fleet-footed Fowler to scamper home.

4. And much like Sunday, the errors were compounded by another costly pitch _ in this case, a 2-2 slider to Matt Carpenter that turned into a three-run homer to right field and a 7-1 deficit.

The Royals had entered the day with the best fielding percentage (.989) in the league. They had committed just 43 errors, the least in the American League by 10, and if you prefer something a little less arbitrarily than errors, they also ranked second in the American League in Defensive Runs Above Average, an advanced metric compiled at FanGraphs.com.

Those numbers, of course, came with catcher Salvador Perez healthy and in the lineup. And they did little to help on Monday. Mike Moustakas clubbed his 32nd homer in the second inning, pulling within four of franchise record-holder Steve Balboni. Eric Hosmer added his 18th homer on an opposite-field blast in the fourth. That was all the offense against Cardinals starter Carlos Martinez, who lasted eight innings and struck out seven. Designated hitter Brandon Moss added another solo shot in the ninth.

On Monday, as the annual I-70 home-and-home series loomed, the Cardinals (56-56) sat one game under .500 and 3 { games out of first, while the Royals occupied the second American League wild-card spot and nipped at the heels of the idle Cleveland Indians.

The Royals once dreamed of the sustainability of their cross-state rival, and two years after claiming a World Series championship _ four seasons after the Cardinals' last title _ they began Monday in position for their third playoff appearance in four years.

They ended the day tied with Tampa Bay for the second wild-card, and perhaps there was an easy lesson to decipher. To get back to October, the Royals must play better defense.