With his roster set for next week’s seven-game Japan All-Star Series, manager John Farrell on Friday began the process of constructing his pitching rotation. This much Farrell knows: He has six starting pitchers at his disposal, two of which — Hisashi Iwakuma and Jeremy Guthrie — he plans to use just once to honor individual club requests. That leaves Matt Shoemaker, Chris Capuano, Franklin Morales and Hector Santiago to fill in the other five games.