Ken Phelps was slow, had no defensive value and didn’t hit for average. But he had two very valuable tools: power and the ability to get on base. He was a very selective hitter who walked a lot, so he was a good OBP guy (.374 for his career) despite a low career batting average (.239). His patient approach also produced a lot of strikeouts and a lot of homers. During his career, he slugged .480 and averaged 26 home runs per 162 games.
Hitters like that are always underrated because they have a low batting average and they look bad striking out one hundred times a year. The funny-looking glasses certainly didn't help Phelps either. As a result, he had to wait a long time to get regular playing time in the Majors. Originally drafted by the Royals, Phelps was traded to the Expos after two shorts stints with Kansas City in 80 and 81. He responded to the trade by hitting 46 homers at the AA level in 1982. But the Expos didn’t think they had room for him. Before the start of the season, the Expos had addressed their need for a left-handed slugging first baseman (which is exactly what Ken Phelps was) by trading third baseman Larry Parrish to the Rangers to get the aging Al Oliver.
Phelps was sold to the Mariners before the start of the 1983 season. For the Expos, he was a missed opportunity. I’m pretty sure they could have plugged him into their lineup as early as 1983 and get good production for next to nothing, freeing up money to address other needs.
With the Mariners, Phelps didn't play right away either. Despite hitting 24 homers in 290 at-bats in 1984, he didn’t play much the next year. But in 1986, at age 31, Phelps played 125 games and did very well despite batting just .247. He hit 24 homers and walked 88 times, posting a .406 OBP and a .526 slugging average. In 1987, he played 120 games and did even better: 27 homers, 80 walks, .410 OBP, .548 SLG.
In 1988, he was traded to the Yankees during the season (for young prospect Jay Buhner) but posted similar numbers: 24 homers, 70 walks, .402 OBP, .549 SLG. He declined rapidly after that, something the Yankees should have anticipated considering his age. It’s just too bad he had such a late start.