Ross is right, and the numbers back it up. According to FanGraphs, the Cubs' rookie position players were worth 11.3 Wins Above Replacement this season, the fourth-highest total in the last 100 years.
Since 1915, only three teams in the Majors have received a bigger boost from their first-year hitters: the 1969 Pirates (13.3 WAR, with four players contributing more than two), the 1924 Pirates (11.9 WAR) and the 1950 Indians (11.5 WAR, including 6.9 from Al Rosen).
In fact, only one team since 1982 can claim a rookie crop that produced a double-digit WAR total: the 2012 Angels, for whom Mike Trout produced 10.