Robert Frederick Hainlen was born on December 18, 1926, in
Trinidad, Colorado. He attended
Trinidad High School and participated in
football,
basketball and
track, winning 10
varsity letters. In track, he competed in the
high jump. The
Deseret News noted that "Bob is but 17 years of age, but it didn't take him long to prove that he is one of the smartest ball players seen around the Colorado Aggie field in several seasons. A
triple-threater, he handles passing assignments, and play-calling like a master, and is a wizard at quick-kicking." Hainlen won his first game against the Colorado State–Greeley Bears (now the
Northern Colorado Bears) by a score of 33–0, serving in addition to quarterback as Colorado A&M's
placekicker and
punter. Four games into the season,
Utah Utes coach
Ike Armstrong declared Hainlen to be the best passer in the
Mountain States Conference (MSC). The team ended the season with a record of 2–5–1. Hainlen remained starter in 1946 and despite the team compiling a record of 2–7, he was called "the region's best passer" and was named an honorable mention all-conference selection at the end of the year. He had become "probably the best kicker in the Rocky [M]ountain region" and "one of the top kickers in the nation" by 1947 and was averaging over 48 yards-per-punt early in the season, a number more than three yards higher than that recorded by whom the
National Collegiate Athletic Bureau (NCAB) listed as the national leader (Hainlen did not qualify for the list due to not having enough punts). He led Colorado A&M to a 5–4–1 record in 1947 and finished as their leading passer and punter, with 468 passing yards on 34 completions and 56 punts for 1,876 yards. As a
senior at Colorado A&M in 1948, Hainlen led the team, who had been projected to finish no higher than fourth (out of six) in the conference, to a record of 8–3 and a second place finish, with only one inter-conference loss to champion Utah. He was noted as having been a key player in several of the wins, including kicking a game-winning
field goal to "stun" undefeated
Utah State 9–7, having "his greatest football performance" in a 21–20 win against undefeated
Wyoming, and a one-score win over
rival Colorado where Hainlen kicked three field goals in what was the margin of victory. He described the Colorado game in 1949 as his favorite, having made all three field goal attempts including a 40-yarder that was the sixth longest in the nation that year. That year, he totaled six fields goals made on 10 attempts as a senior, tying for what was then the national record for field goals made in a season. Hainlen was selected second-team all-conference at the end of the season, with the
International News Service (INS) noting that he gave
Cannon Parkinson a "run for the spot" on the first team. He was ruled ineligible to play in the 1949 season after eligibility issues due to
World War II were "ironed out". Despite his ability in kicking field goals, Hainlen noted in a 1949 interview with
Al Cartwright that he was unable to kick shorter
extra points. Colorado A&M coach
Julius Wagner called Hainlen "the greatest all-around athlete I've ever seen", further elaborating: ==Professional career and later life==