Andrew Cashner, San Diego Padres, April 24, 2014
Padres left fielder Seth Smith suffered some sort of leg injury either fielding a ball in the bottom of the 10th inning or while running out a ground ball in the top of the 11th.
The Padres had several position players remaining on the bench, but Cashner replaced Smith in LF to start the bottom of the 11th. This lasted for only one batter; after Jayson Werth lined out, the Padres double-switched Cashner and reliever Tim Stauffer (who was due up 3rd in the 12th) out of the game for new LF Tommy Medica and P Alex Torres.
Details of other pitchers used in the field can be found here.