[7] No National Football League team showed interest in the undersized center, who weighed only 205 pounds.

[10] He won one AFL/AFC championship in 1967 against the Houston Oilers with the Raiders,[11] but lost five: in 1968,[12] 1969,[13] 1970,[14] 1973,[15] and 1974[16] to the New York Jets, Kansas City Chiefs, Baltimore Colts, Miami Dolphins, and Pittsburgh Steelers, respectively, with all five teams winning the Super Bowl.

[17] In the 1967 regular season, Oakland scored 468 points (33.4 points/game), leading the AFL, but lost Super Bowl II to the Green Bay Packers.

In 1968, Oakland scored 453 points (32.4 points/game) in the regular season, again leading the AFL, and beat the Chiefs in the divisional round (unscheduled tiebreaker) before losing to the Jets.

In the 1970 regular season, the first year of the NFL-AFL merger, Oakland scored 300 points (21.4 points/game), ranking ninth in the 26-team NFL, and beat the Miami Dolphins in the AFC playoffs before losing to the Colts.

The Raiders came back stronger in 1972, scoring 365 points (26.1 points/game), ranking third in the NFL, but lost 13–7 to the Pittsburgh Steelers in the divisional round of the AFC playoffs, the famous Immaculate Reception game, in which Otto also made the only pass reception of his professional career.

In the 1973 regular season, Oakland scored 292 points (20.9 points/game), tenth in the NFL, and avenged their defeat to the Steelers, but lost to the Dolphins.

In Otto's final year, 1974, Oakland scored 355 points (25.4 points/game), leading the NFL, and avenged their playoff loss to the Dolphins, but lost to the Steelers again.

[20] During his career, the Raiders won seven divisional championships from 1967 through 1974, and were AFL champions in 1967, meeting the Green Bay Packers in Super Bowl II.

[10] Otto's offensive linemates with the Raiders included hall of famers Gene Upshaw, Art Shell, and Bob Brown.

[22] In 2019, he was revealed as being selected to the National Football League 100th Anniversary All-Time Team, being one of only four centers named.

[25] In his book, The Pain of Glory, Otto described near-death experiences from medical procedures, including fighting off three life-threatening infections due to complications from his artificial joints.

[27][28] After his career, Otto worked for the Raiders during two periods, and then made a "small fortune" from Burger King franchises, liquor stores, a walnut orchard, and real estate in the Oakland area.