KANSAS CITY -- It wasn't nearly as drastic as the major renovations that took place before the 2009 season, but there was a slight alteration made at Kauffman Stadium this offseason.

A pair of chain-link fences that sat atop the outfield wall in left- and right-center fields have been covered with padding, raising the padding in those two locations over the out-of-town scoreboards.

Why the change?

"We wanted to try to simplify the process for umpires in terms of what's a home run and what may be a ball that's still in play, particularly since there was some confusion last year," said Dean Taylor, the Royals vice president of baseball operations.

Since home run reviews were instituted in 2009, there have been six reviewed hits at Kauffman Stadium. Each time, the original call has been upheld, including three home runs off Royals' bats last season.

• June 13, 2009: Billy Butler smashed a ball down the left-field line, and it cleared the wall by a wide margin. But, the hit was called foul. After Trey Hillman spoke with the umpiring crew, a review was conducted, and the call was upheld.

• Sept. 10, 2009: Alberto Callaspo hit a ball over the fence on top of the wall in right-center field. A fan leaned over the railing, getting a hand on the ball, and Jim Leyland talked with the umpires, leading to a vide review. The umpires saw that the ball had cleared the fence prior to the fan touching it, and Callaspo's homer was upheld.

• June 1, 2010: Hideki Matsui, playing for the Angels, launched a ball into the right-field corner that ricocheted off the small fence at the top of the outfield wall -- a feature that still remains at Kauffman Stadium -- and all the way into right-center field. The hit was ruled a double and upheld after video review.

• June 1, 2011: One year later, Butler hit a ball into left-center field that bounced between the fence and the railing, going for a home run. The umpires reviewed the hit and upheld Butler's walk-off winner.

• Aug. 17, 2011: Butler was at it again, this time hitting a ball that appeared to bounce off the fence on top of the outfield wall in left-center and back into the field. Umpires misinterpreted a ground rule, calling the hit a home run before and after video review.

• Sep. 17, 2011: The most recent hit to be reviewed was Mike Moustakas' home run against the White Sox. Again, the ball landed in between the fence and the railing, leading opposing manager Ozzie Guillen to inquire about a review. The call was upheld.

One notable incident from 2011 was Billy Butler's reviewed home run on Aug. 17 against the Yankees. The ball appeared to hit off the then-top of the outfield wall's padding and back onto the field. Because of a misinterpretation of a ground rule, the hit was initially ruled a home run and upheld after video review.

But umpires still were having a tough time seeing the plays as they happened.

"You've got the silver railings and the silver fence. And you've got a silver railing behind it. And then you've got people wearing black pants, white pants, green pants, pink pants, white shirt -- all these different colored backgrounds," said Steve Palermo, a supervisor of Major League umpires. "Well as you can see, if you look at that fence now, you can't see what somebody has on as far as a shirt. All you are is looking for the ball. And what an umpire's looking for is if that ball disappears, and you lose sight of that ball, even for an instant, then you know that that ball went behind the fence."

The sight line, at least in left-center, is now much better for those on the field, as the padding not only covers that chain-link fence, but obstructs the view of a recessed railing separating the first row of seats from the outfield wall. While the same change was made to the wall in right-center, the recessed railing is still visible from the field because it is higher than the one in left-center.

"We didn't want to make it any tougher to hit a home run than it already was," explained Taylor, on why the right-center field padding wasn't raised to obstruct the higher railing.

Fans watching Saturday night's game between the Royals and Indians might have noticed the new padding. Shin-Soo Choo's 10th-inning, game-winning double hit the new padding and bounced back into the field. Had the new padding not been installed, the hit would have been nearly identical to Butler's home run against the Yankees last season.

For those scoring at home, all that's required for a home run in those parts of Kauffman Stadium is for the ball to clear the new padding. If it hits the top of the wall and bounces over, it's a home run. If it hits the top of the wall and bounces back onto the field, it's in-play.

"Our goal is to make [the umpires'] jobs as easy as we can," Taylor said. "The design we have now is the design we had hoped to get originally when we did the renovation. For whatever reason, it didn't turn out that way, so we wanted to make sure we did that. Particularly with the All-Star Game coming up this year, we wanted to make it as umpire-friendly, as fan-friendly, as media-friendly as possible."

According to Palermo, the park is much more umpire-friendly resulting from the changes.

"This is still one of the nicest, cleanest ballparks as far as people around the ballpark interfering with baseballs or not interfering with baseballs," Palermo said. "We want the players to decide the game, not a fan reaching over and interfering with a baseball. And that was one of the reasons why we did go out there and have that remedied."