MacLellan had some great talents. He was absolutely huge at 6'3" and 215 pounds of chisled muscle. He was as strong as an oak tree, immovable in front of the net. He wasn't a fast or graceful skater, but had power and balance in his stride to make up for that. And he possesed excellent puck skills, most notably his shot. He had an overpowering wrist and slap shot, which he got off with great quickness and accuracy.
When he was fired up, Brian had the capability of dominating a single game. Problem was he rarely seemed to get fired up. He had the strength and the talent, but he lacked the intensity and consistency to truly become one of the league's top left wingers in the 1980s. Despite his size he wasn't an overly physical player by nature. And defensively he was a liability - partly because of his lack of speed but also do the sheer laziness and poor positional play.
As a result of his frustrating label, Brian was a well traveled NHLer, playing with 5 organizations in 10 years. He started out with the LA Kings, and enjoyed his best season statistically in 1984-85 when he scored 31 goals and a career high 54 assists and 85 points. However early in the 1985-86 season he was traded to New York and the following season to Minnesota. Late in 1988-89, he was traded to Calgary and played a minor role in their first Stanley Cup championship. He spent 2 more years in Calgary before playing one final season with the Detroit Red Wings in 1991-92.
No one should question Brian's work ethic or desire. To play in the NHL as long as he did takes tremendous amounts of both. Brian was more complacent than anything. He could have been a great left winger in the league.
The fact that MacLellan played in the NHL is a miracle in itself. As a child he suffered from a bone disease that left him in a body cast for a year. And when he was 19 he broke his neck. Two times in his young life he almost became permanently paralyzed.