Boyd game 1, Taillon game 3. Between Shota and Rea, I could see either getting the nod.
Rea has been good lately, is much better vs RHB than LHB. Shota struggling lately but slightly better vs LHP than RHB but mostly even splits. Padres have a good mix of LHB and RHB, though their big sluggers are RHB. I imagine the Cubs will look at the individual matchup numbers too, especially vs Rea who's been around the league a while.