That's right, the bowling ball Robert Newhouse. I'm going to go off on a tangent now. Robert Newhouse was drafted in the 2nd round that year. Another RB, Bill Thomas (No relation to Duane) was drafted in the 1st round, ended up being a bust.
Anyway, from the 30's to the end of the 70's the first game of the preseason was not the Hall of Fame game. It was actually the SB Champion-College All Star Game.
That's right, the SB champions would play a team made up of the best players they just drafted. Well, in 1972, the champions of the 71 season was the Dallas Cowboys. Robert Newhouse was on the All Star team. The Champions always won the game in the 60's and 70's as the NFL became more sophisticated. The Dallas Cowboys won 20-6. The All Stars scored a TD and it was Newhouse.
Robert Newhouse wasn't always the FB. He was a RB in his first 3 seasons but Tom Landry always had a habit of experimenting with the two back system. He often had a "tweener" who would spell both backs or in some cases he just wanted to get the two best backs on the field.
He did the same thing previously with Duane Thomas, Calvin Hill, and Walt Garrison. Quite often he would put both Thomas and Hill on the field together in which case it was always Duane who switched to FB.
The first season Newhouse became a full time FB was 1975. The Cowboys wanted to start the RB they got from the Steelers, Preston Pearson because he was also a great receiver (unrelated to Drew Pearson). In 1975, as you noted, Newhouse was the leading rusher but they got contributions from 4 other backs including Roger Staubach.
Of course, after the Cowboys drafted Dorsett, Newhouse was a pure FB. That doesn't mean he didn't carry the ball, for the next five seasons he got anywhere from 300 to 700 yards a season.
Anyway, below is a link to a S.I. story about that preseason game between the SB champions and College All Stars. It's wrapped around a story involving an offensive lineman by the name of Jackie Slater, a HOFer that played 20 seasons. However, his first taste of the NFL was as a rookie All Star playing against the SB champion Steelers. As an O-lineman, his assignment was HOFer Mean Joe Greene.
https://www.si.com/nfl/2015/12/08/college-all-star-football-classic-jackie-slater-joe-greene