Expos trade Zane Smith to the Pirates for Moises Alou, Scott Ruskin and Willie Greene.
In a tight race for the NL East crown and in desperate need of another starting pitcher to flank ace Doug Drabek, the Pirates dealt one of their top prospects in Alou to acquire Smith.
The Pirates got what they wanted, as Smith was brilliant down the stretch (10 starts, 6-2, 1.30 ERA), helping propel the Pirates into the playoffs. While they bowed out to the Reds in the NLCS, the Pirates season was still a successful one.
Smith earned himself a four-year contract in the offseason with the Pirates, and he responded with a 16-10 campaign the following season and overall went 47-41 in parts of six seasons in Pittsburgh.
Alou was a full-time starter for the Expos by 1992 after being the "player to be named later" of the deal, and he would enjoy a terrific 17-year career that saw him make six All-Star teams and hit .303 BA, 332 HR, 1,287 RBI playing for seven different teams.
Greene and Ruskin were actually packaged together in another trade following the 1991 season, as the Expos shipped them to the Reds for closer Todd Wetteland.
Greene went on to be the Reds' starting third baseman, peaking in 1997 with a .253 BA, 26 HR, 91 RBI season that was by far the best of his nine-year career.