Ryan also walked twice as many batters as the next-highest pitcher. Some (eventually) viewed his pitching as selfish - never giving in to the batter, either striking him out or walking him. Not much for his fielders to do. Rather give up 3 walks than allow a hit.
His '87 season is the oddest ever: 8-16 win/loss record, but led the league in ERA and Ks. What sense does that make?
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All-time leader in strikeouts, walked batters, and hits per 9 allowed. That's basically all you need to know about him.