SCOTTSDALE, Ariz. — After decades of watching home runs fly out of Coors Field at a heightened clip, the Rockies on Tuesday said they will raise their outfield fences to tamp down on the longballs.

The high-homer home of the “Blake Street Bombers” will get its biggest change to how baseball is played at altitude since a humidor was installed in 2002.

“The goal is to raise the wall heights to make it potentially more playable and more fair — for pitchers,” Rockies general manager Jeff Bridich said. “We really don’t know, exactly, the effect it is going to have. We are going to live it together, this year, and see what happens.”

The Rockies will raise their outfield wall between right-center and right field by 8 feet and 9 inches, to match the height of the out-of-town scoreboard, at 16 feet-6 inches in height. A green-coated, chain-link fence will sit on top of the existing green-padded wall in front of the visiting and home bullpens.

The outfield wall height also will increase down the left field line, by 5 feet, to 13 feet. That extended fence will be in front of the tunnel next to the bleachers.

The new fences, which will not block any seats, will be installed this month and be in place before the Rockies’ 22nd home opener at Coors Field, on April 8 against the Padres.

“I have thought about this for a long time,” Rockies manager Walt Weiss said. “I thought it would eliminate some of the cheaper home runs that we see there. And if you could keep a ball in the park here or there, it could change some things.”

Over the past three seasons, teams have hit 570 home runs at Coors Field, the most in the National League. Three American League ballparks, with the benefit of the designated hitter, netted more home runs: Camden Yards in Baltimore (629), Rogers Centre in Toronto (603) and Yankee Stadium in New York (571).

The Rockies, Bridich said, determined that right-center field and down the left field line were high-home run areas. They used a formula that accounts for the launch angle and exit velocity of hits off the bat to figure out how to reduce easy homers. By that measure, total home runs at Coors Field could fall by 5-6 percent.

“We had two decades worth of knowing this ballpark,” Bridich said. “There have been a lot of ideas thrown out over time about what should be done, if anything. One of the nice things now is that with all of the advancements in technology, there is a lot of data and data sets that we can point to.”

The left-field fence in front of the bleachers, an area that sees its share of “Coors Field home runs” will not be changed — yet.

“We thought that this could be a first step in a number of steps, potentially. We just don’t know,” Bridich said.

Rockies players reacted as if a stranger rearranged their living room furniture. Right fielder Carlos Gonzalez, who hit 40 home runs in 2015, third most in the NL, said he would have lost one homer last year with the higher walls. He said he remembers it exactly — a line drive off a Carter Capps slider against the Miami Marlins on June 7.

Colorado center fielder Charlie Blackmon was not pleased. He expects to lose “probably a couple” home runs this season with the higher walls. And outfielders, having to play caroms off a new wall, might have a long learning curve.

“Balls that hit the fence are now going to bounce like they hit a chain-link fence, which isn’t always predictable,” Blackmon said. “It’ll kill the bounce. So you’ll see outfielders have to go farther out to field the ball, which could allow more triples.”

Before the humidor was introduced in 2002, Coors Field experienced three of the four highest single-season home run totals in baseball history — topped by an MLB-record 303 in 1999. In the five years after, home run totals fell each year to an all-time low of 168 in 2006.

If higher outfield walls have a similar effect, the look of the Rockies — and their identity — could swing farther away from their reputation as “Bombers.”

“It’s a good place to start,” Weiss said of the new fences. “To do anything more, you are talking about some radical changes. You would have to start reconfiguring the ballpark. I really haven’t gone down that road yet.”

Nick Groke: ngroke@denverpost.com or @nickgroke