Mark Langston: 1981: Round 2, Pick 35, 19.2 (50.0) WAR
This was foreshadowed earlier, and makes me realize that the Mariners crushed it that year in the draft. Knowing that you get Mike Moore and then Mark Langston in back-to-back rounds is really impressive. Especially when the guy you drafted later was the better one, and the main reason for the Mariners acquiring one of the most dominate pitchers in the history of baseball via trade.
With Langston, though, the Mariners found another innings eater. This one had good strikeout stuff as well. Langston actually led the American League in strikeouts in three of his first four seasons, tallying 204, 245, and 262. It sounds like a lot, and it is, but is helped when you throw 225, 239.1, and 272 innings over those seasons.
While he was good with the Mariners, he was also quite wild. He would walk 4.3/9, a total of 575 walks across 1197.2 IP between 1984-1989. The best years of his career would come with the California Angels from 1991-93, when he would amass a combined 19.0 WAR, with two seasons above 7.3.
The next six, which were the last six he threw, something changed. He was never below a 4.63 ERA and had a total ERA of 4.99 and a WHIP of 1.496. He still goes down as one of the best players the Mariners have ever drafted, and would be, if not for two of the all-time greats to ever play the game of baseball.