Arenas was, along with Tom Fears and Eddie Saenz, among the first Mexican-American players to achieve significant success in the sport of American football.

[6][8] Arenas credited his military background with giving him the mental and physical toughness that led to his success in football.

[11] Arenas also played basketball at Omaha; he was the team's second leading scorer in 1950 with 144 points on 56 field goals and 32 free throws in 23 games.

He is an inspirational holler-guy who can lift flagging spirits; who refuses to be whipped even if the score is top-heavy in the other side's favor.

Team devotees feel a sense of complete confidence watching a well kicked ball sail in the direction of Arenas, playing safety.

On those rare occasions when the spinning ball briefly twists out of his waiting arms, he is on the pellet with the speed of a mongoose.

[19] A columnist for the Oakland Tribune in July 1958 wrote that the 49ers lineup would not be the same without him and added, "Arenas has a spectacular quality which appeals to the customers.

"[20] After he announced his retirement, the Oakland Tribune called him "a scrappy little back" who "made up with hustle what he lacked in ability" and became "the most popular player on the 49ers.

[22] His 4,572 career kick and punt return yards was the best in NFL history at the time of his retirement;[23] Al Carmichael broke his record in 1958.

In December 1958 Arenas wrote that he had been banned from the 49ers' bench and dressing room for things he had written in his newspaper column.

According to Arenas, team owner Vic Morabito claimed that his former teammates "had not appreciated my comments about their playing.

"[6] In March 1961 the Santa Clara County Sheriff's Department issued an all points bulletin for Arenas after he was charged with forging a business partner's name on a $264 check at a Bank of America branch in San Jose, California.

[26] In June 1961 Arenas was ordered to stand trial in San Jose, California on a forgery charge.

[8] From 1991 until at least 2002, Arenas served as an unpaid volunteer coach with the Ball High School football team in Galveston.

[30] Arenas was also profiled in Mario Longoria's 1997 book, "Athletes Remembered: Mexicano/Latino Professional Football Players, 1929–1970.