When a hitter achieves a barrel in Colorado, how much of a difference does the thin air have on its outcome?

Everyone knows the narrative: If someone on the Colorado Rockies is putting up monster offensive numbers, it’s solely due to their home ballpark. That’s what everyone says. “Coors…” is keeping Larry Walker out of the Hall of Fame, and could be skewing our judgement of current Rockies like Nolan Arenado and Charlie Blackmon.
The question is… “Is it a fair criticism?”
How much does Coors actually play an effect on batting and pitching numbers? Is the Coors effect overstated, or is it actually understated? Do we understand what’s going on here?
It has been postulated the thin air in Coors makes fly balls and line drives fly 10 percent further. It’s closer to seven, but it ultimately depends on how the ball is hit.
Looking at all barrels hit in baseball the last two seasons grouping them by launch angle and exit velocity, we can look how much further balls went at Coors compared to similar batted balls in the other 29 parks.

Ultimately, the magnitude of the Coors effect depends on the launch angle and exit velocity. Generally the harder the ball is hit, and the higher it is hit, the more Coors effects it.
Seven percent doesn’t seem like a lot. If a ball goes seven percent further, is that a lot? Well, yes; it’s about 25 feet in most cases, depending on what the average distance is. Sometimes it could be up to 40 feet.

This definitely matters. Besides a couple outliers with the angle less than 20 degrees, most every barrel flies significantly further at Coors Field. It’s hard to believe one ball hit 100 mph at 30 degrees can fly 30 feet further than another ball hit the same at another stadium.
That distance difference could mean the difference between a warning track fly out and a no doubt, upper-deck home run, and certainly explains part of the reason why hitters put up significantly better numbers at Coors.