Common wisdom holds that for the Colorado Rockies to excel while playing home games at mile-high Coors Field they have to lead the Major Leagues in runs scored. They have to out-bash every other team and win a bunch of 10-9 games on their way to a 900-run season that eases the impact of a pitching staff full of bloated ERAs. But as of Sunday morning, Colorado is 41-23, with the best record in the National League, and their success has as much to do with pitching and defense as with slugging. Make no mistake, the Rockies can hit. Nolan Arenado is a stud, Charlie Blackmon is having an MVP-caliber season and Mark Reynolds is breaking out at age 33. But thanks to slumps from DJ LeMahieu, Trevor Story, Ian Desmond and Carlos Gonzalez, Colorado does not lead the Majors in runs per game. In fact, the Rockies rank only fourth in that category (behind the Astros, Yankees and Nationals) and are on pace to score only a few more runs than they did in 2016, when they went 75-87. The difference for this Colorado team has been run prevention. Despite playing half their games at altitude, the Rockies have allowed fewer runs per game (4.14) than all but four other teams. If they maintain that rate over a full season, they will give up fewer runs than any Rockies team ever has during a 162-game campaign. That success in keeping opposing lineups at bay begins with an overachieving young starting rotation. 22-year-old rookie Antonio Senzatela has a 3.56 ERA and 4.40 FIP. Another rookie, 24-year-old Kyle Freeland, has a 3.34 ERA and 4.59 FIP. Yet another rookie German Marquez, has a 4.44 ERA and 3.91 FIP. Jeff Hoffman is technically not a rookie, but he is a 24-year-old with a 2.33 ERA and 2.46 FIP.