Remember, we are talking about Game #1 only.
Many times you will see veterans starting game #1 but eventually a rookie will start at some point in the season.
A player is considered he starter for that season if he starts more than half of the regular season games.
In game #1 in 1989 it wasn't Mark Stepnoski who started at center for game #1, it was veteran Tom Rafferty. Daryl Johnston didn't start at FB, it was Kevin Scott. Too Tall Jones and Jim Jeffcoat were the starting DE's, Tony Tolbert started 5 games that season.
In 1975 only one rookie started in game #1 and it was LG Burton Lawless. Contrary to popular belief, the 1975 team didn't really feature the rookies. However, the rookie class played significant roles on special teams, nickel packages, and 3rd down defense.
In 1975 the Cowboys drafted their future LB squad, Hollywood Henderson, Bob Breunig and Mike Hegman. All 3 started zero games that season.
The Cowboys drafted two perennial starters on the offensive line, Pat Donovan and Herbert Scott. However, in their rookie seasons they started a combined 5 games.
Even future Hall of Famer Randy White only started 1 game that season.