6. Frank Tanana

Frank Tanana arrived in Anaheim as a left-handed lightning bolt, a pitcher whose early velocity was so pure it rivaled the thunder of his teammate, Nolan Ryan. While history often places him in the shadow of the "Express," Tanana was a statistical giant in his own right, providing a specialized brand of southpaw dominance that the American League had rarely seen.

Tanana’s rise in California began with a 1973 debut, but he reached a career-defining breakout in 1975. That season, the 21-year-old left-hander led the American League with 269 strikeouts and a league-best strikeout-to-walk ratio, signaling his transition from a young prospect to an elite rotation force. He possessed a focused intensity on the mound, pairing a blistering fastball with a devastating curve that made him a nightmare for hitters across the junior circuit. He provided high-frequency power, recording over 240 strikeouts in three consecutive seasons while keeping his ERA well under the 3.00 mark.

In 1977, Tanana reached a career peak, leading the American League in ERA (2.54) and pitching bWAR (8.3). Despite these massive numbers, the traditional voting of the era overlooked his dominance, placing him ninth in the Cy Young race while favoring relievers and high-win starters. He showed the organization that a pitcher could lead the league in efficiency and workload simultaneously, as he also led the AL in shutouts (7) that year. He demonstrated craftsmanship, proving that his left-handed delivery was every bit as lethal as the right-handed heat coming from the other side of the Angels' rotation.

Everything culminated in 1979, when Tanana provided the veteran-like poise that helped California reach its first-ever postseason. However, the heavy workload of his early twenties began to take a physical toll; a bout of tendinitis forced a tactical shift, as he moved away from his power-pitching roots and began to navigate a different plateau as a finesse artist. He was eventually dealt to the Red Sox before the 1981 season, leaving Anaheim with 102 wins and 1,233 strikeouts.