He opened two games a year ago against the Astros, allowing two earned runs in 8 2/3 innings without getting a decision.
His move to start Friday's game is to put designated hitter J.D. Martinez in left field, moving Andrew Benintendi to the bench.
The three-time World Series champion hasn't been shy in sharing his political opinions since retirement, often with career consequences.
WEEI host Lou Merloni shined a light on the hometown hero's good deeds late Thursday night, reporting Betts provided trays of food for the homeless outside the Boston Public Library following Game 2.
Game 3 starts at 8 p.m. ET, and will air on Fox.
The Internet search engine Friday returned some curious results for people looking up the terms "Red Sox World Series" and "Red Sox Championships".
Martinez rolled his right ankle on a double in Game 1. He stayed in, then delivered a key hit Wednesday night in Game 2 at Fenway Park.
It wasn't the first time Betts has made a similar gesture.
"Walker is a tremendous talent", Kershaw said after the NL tiebreaker game.
Cora flatly said Betts would not start at second base.