With the Texas Rangers and San Francisco Giants facing off beginning Wednesday, Bengie Molina joins a select club of players that were dealt midseason only to face their former team in the World Series. Molina hit .257/.312/.332 in 61 games with the Giants, and hit .240/.279/.320 in 57 games with Texas. In the postseason, Molina has 10 hits in eight starts this year for the Rangers, hitting .333/.355/.567 with two home runs and seven RBI.
There has only been one other player who played in the World Series against the team they played for earlier in the season, at least dating back to 1952:
1985: Lonnie Smith
Smith won a World Series with the 1980 Phillies and 1982 Cardinals, and began the 1985 season in St. Louis. He was hitting .260/.377/.323 when the Cardinals dealt Smith to the Royals for future impersonator extraordinaire John Morris. Smith hit .333/.400/.444 with three doubles against St. Louis in the World Series, won by Kansas City in seven games.
There have been other players that have been acquired midseason in a transaction between eventual World Series teams, but these players didn't play in the postseason:
2010: Chris Ray
Ray went the other way in the Molina trade, but has yet to pitch a postseason inning for the Giants
1998: Jim Bruske
The reliever began the 1998 season with the Dodgers, and was traded to San Diego on July 23 for the immortal Widd Workman. However, Bruske only pitched seven innings before being traded to the Yankees exactly one month later. Bruske pitched nine regular season innings with New York, but didn't pitch in the playoffs, as the Yankees swept the Padres in the World Series.
1995: Eddie Tucker
Tucker was a 28-year old journeyman catcher who began 1995 with Houston before being traded to the Cleveland Indians for no-not-that Matt Williams. Tucker went hitless in 20 at-bats with the Indians (plus five walks, a hit-by-pitch, and a sacrifice fly) before being selected off waivers by the Braves on June 29. Tucker never played in the majors again, missing the Braves' six-game World Series win over the Indians.
1984: Sid Monge
It turns out Monge is known for more than giving up the first hit of Tony Gwynn's career. Monge was in the final season of his career in 1984, starting the year with Gwynn and the Padres. But on June 10, 1984, San Diego sold Monge to the Tigers, who would go on to beat the Padres in the World Series.
1983: Paul Mirabella
Mirabella was a 29-year old pitcher that signed with the Orioles in April 1983, but only pitched 9 2/3 innings for them during the season. On August 12, the Phillies purchased Mirabella from the Orioles, but he never made it into a game for Philadelphia. Baltimore beat the Phillies in five games in the World Series that year.
1952: Johnny "Bear Tracks" Schmitz
Schmitz began the 1952 season with Brooklyn, and the 31-year old was 1-1 with a 4.32 ERA in 33 1/3 innings with the Dodgers. Bear Tracks was selected off waivers by the Yankees on August 1, but was dealt later in the month in a 4-for-1 deal for Ewell Blackwell. Blackwell gave up four runs in five innings to the Dodgers in Game 5 of the World Series, a game eventually won by the Dodgers 6-5 in 11 innings. The Dodgers held a 3-2 series lead, but lost to the Yankees in seven games.
Thanks to Baseball-Reference.com for some of the data.