In his only season with the Cardinals-2005-Abraram Nuñez, who hit .238 for his Pirates career, had to take over 3B when Scott Rolen was lost due to injury at mid-season. Nuñez hit .285 for the Cards and then batted .364 in the NLDS and .385 in the NLCS. After the season he signed with the Phillies as a FA and returned to his light-hitting ways (.211). 2005 was 1 of only 3 seasons when Nuñez hit above .236.
Baseball is a funny game. Mark Belanger, a career .228 hitter, once batted .287. Chris Stewart came to the Pirates in 2014 as a career .214 hitter and had batted .211 in 2013 for NY. But with the Bucs in 2014 and 2015 he hit .294 and .289 with almost all soft singles. Then down to a more characteristic .214 in 2016. Sometimes even a bad hitter's luck can hold out for an entire season. Austin Hedges once hit a career high .231 (1 of 2 seasons above .178).
Did anyone see who hit the game-winning dinger for the National League in the AS game? None other than 32-year-old Elias Diaz in his first (and likely only) all star appearance. Good for him!