Over the course of the next five years, Bales' ranking declined steadily as he was able to produce only intermittently good results. He reached the last 32 in three more ranking events - the 1987 Grand Prix, where he lost 2–5 to Willie Thorne, the 1989 British Open, where Mike Hallett whitewashed him 5–0, and the 1989 International Open, where he was beaten 5–1 by Alain Robidoux - but, having begun the 1991–92 season ranked 116th, he finished it, having lost 1–10 to Chris Cookson in qualifying for the 1992 World Championship, without a ranking.