After a promising 4-3, 2.41 season for Baltimore in 1968, Nelson was the Royals’ first pick in the expansion draft. He was 7-13 despite a 3.31 ERA as their number-four starter in 1969 and then spent most of 1970 on the DL with shoulder trouble. He made it back in 1972, and was 11-6 with the fifth-best ERA (2.08) in the AL. On August 23 he pitched a one-hitter against the Red Sox (Ben Oglivie singled in the seventh inning). That winter he was traded with Richie Scheinblum to Cincinnati for Hal McRae and Wayne Simpson. Nelson sat out much of the rest of his career with injuries, pitching well when healthy.