He suffered two severe injuries during the 81-82 season, and just did not look like the same player during the 82-83 season. The eye injury was brutal, I recall an interview after he came back saying he was having trouble with depth perception (and it looks like that eye was often dilated), and he had a serious groin pull that effected his skating. He wasn't a speed demon to begin with, but he definitely looked sluggish in his last season with the Flames, and really was only effective on the PP. Plus, the Flames had locker room problems starting with the 81 playoff run when coach Al MacNeil criticized Kent Nilsson publicly in the media, calling him "magic" for "disappearing," which the media ran with. Willi Plett, who was linemates with both Chouinard and Nilsson, thought MacNeil was unfair and out of line for picking on Nilsson specifically, and led a revolt against MacNeil, which eventually ended up with Plett and a couple of others being traded, and may have contributed to MacNeil's firing, as the locker room troubles apparently lasted the entire 81-82 season. It is likely that Chouinard was seen as part of the "Plett clique" and Cliff Fletcher decided to move on from him as soon as possible, and the injuries and subsequent decline in play likely did him no favors. Fletcher started making moves to get guys he felt were more solid "character players" like McDonald, Risebrough and Mel Bridgman.
At his peak, he was fun to watch, a pure finesse player who really seemed to have no trouble gelling/producing with any of his linemates with the Flames, and could drive offense. He was a great passer and could at times be sneaky around the net. He also could play all three forward positions effectively if called on, so during his 4 seasons as Nilsson's primary linemate they often switched positions depending on who their primary winger was (Plett, McDonald, Bob MacMillan, Eric Vail, Jean Pronovost). When the Flames first moved to Calgay he was the player I liked best at the outset.