If Shields is a 2, Radke was a 2. The difference in ERA is a function of the differences in league ERA. Radke's was .43 better than the average of his leagues; Shields was .45 better. Top 6 seasons by bWAR: Radke: 6.5, 6.2, 5.8, 5.2, 4.6, 4.5 Shields: 5.5, 5.2, 4.1, 3.8, 3.3, 2.7 Top 6 seasons by ERA+ Radke: 136, 135, 120, 116, 115, 114 Shields: 134, 131, 124, 123, 117, 109 Differing styles, but very similar results. (If you go beyond 6 seasons, the results favor Radke more. Shields still has an arm attached to the body, so the analysis could change.)