Valencia is one of three third basemen on the roster, joining Arizona's Ryan Roberts and San Francisco's Pablo Sandoval. Valencia, 27, hit .246 with a .294 on-base percentage and .383 slugging percentage with 15 homers and 72 RBIs in 154 games.
Butera, 28, joins Angels backstop Jeff Mathis as one of two catchers on the roster. Butera batted .167/.210/.239 with two homers and 23 RBIs in 93 games.
The roster is headlined by Yankees center fielder Curtis Granderson -- who led the Majors in runs scored (136) and ranked second in home runs (41) -- and his teammate Robinson Cano, who was second in the American League with 118 RBIs. Tigers first baseman and AL batting champion (.344) Miguel Cabrera, who is currently playing in the AL Championship Series, will make the trip if postseason commitments allow.
Others on the roster, which is not yet complete, are infielders Erick Aybar (Angels), Michael Morse (Nationals) and Skip Schumaker (Cardinals); outfielders Emilio Bonifacio (Marlins) and Logan Morrison (Marlins); and pitchers Bill Bray (Reds), Ross Detwiler (Nationals), Dillon Gee (Mets), Jeremy Guthrie (Orioles), Mark Melancon (Astros) and Jose Veras (Pirates).
Giants manager Bruce Bochy, who last year guided his club to its first World Series championship since 1954, will manage the MLB All-Stars. His coaching staff will be composed of Giants bench coach Ron Wotus, Giants bullpen catcher Billy Hayes, Dodgers pitching coach Rick Honeycutt and Rays hitting coach Derek Shelton.
The remainder of the roster will be announced in the coming weeks.
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, and follow him on Twitter @RhettBollinger. This story was not subject to the approval of Major League Baseball or its clubs.