Gwynn Jr., who has played parts of eight seasons in the big leagues and spent time with the Phillies last year, signed with the Nationals on March 2. The 32-year-old has spent the season in Syracuse, batting .228, but he came through in a big way on Sunday.
In the bottom of the 10th inning, Kevin Keyes led off with a single and moved to second on Rick Hague's sacrifice bunt. That set up Gwynn Jr., who hit a ground ball into right field off Buffalo left-hander Andrew Albers, scoring Keyes for the game-winning run.
Only five days earlier, the baseball community observed the one-year anniversary of Gwynn's death, which came after a battle with salivary gland cancer.