After posting a 4-0 record with a 0.73 ERA (3R/37IP) in July Chris Archer  was named the American League Player of the Month and Pitcher of the Month. The key to his success in July and moving forward is controlling left handed batters.
Over his first 4 starts he posted a record of 1-3 with an ERA of 5.03 (11ER/19.2 IP) allowing 3 HR striking out 18 and walking 14. The damage can mostly be tracked back to left handed batters who took advantage of him hitting .278 (15 for 54) with 3 home runs striking out 9 times while walking 10. During that same period of time he held right handed hitters to .143 (3 for 21) average without allowing a home run while striking out 8 and walking 5.
On the season he has dominated right handed batters holding them to an average of .141 (14 for 99) with only 1 home run while striking out 16 and walking 11. He has held them to a paltry slash line (batting average/on-base%/slugging%) of .139/.237/.182 with an OPS (on-base% plus slugging%) of just .419.
On the others side the results haven’t been as stellar. Left handed hitters are hitting .236 (39 for 165) with 6 home runs striking out 35 times and walking 17 and posting a slash line of .236/.316/.424 and an OPS of .740
Teams continue to load the lineup with left handed bats. In his last start against the San Francisco Giants he had to face Gregor Blanco , Pablo Sandoval , Roger Kieschnick , Brandon Belt , and Brandon Crawford  and the group came to the plate 16 times delivering 5 hits including 2 home runs and drove in all 4 runs in the Giants 4-1 victory.
His success over his last 7 starts can be attributed to how he has been able to dominate right handed bats but more importantly he has controlled left handers holding them to a .216 average (24 for 111) and a slash line of .216/.276/.387 with 3 home runs striking out 25 and walking 8 (one intentional).
In his last start against the San Francisco Giants he went 7 innings allowing 4R/ER on 7 hits striking out 4 and walking 3. He allowed 2 home runs the first of which ended a string of 37 innings without allowing a home run. Like most managers do against Archer Bruce Bochy  loaded his lineup with five lefties (Gregor Blanco , Pablo Sandoval , Roger Kieschnick , Brandon Belt , and Brandon Crawford ) and the group combined to go 5 for 16 with 2 home runs driving in all 4 runs on the night.
With his success against right handed hitters it stands to reason that he is going to continue to see as many lefties as possible. On Wednesday night Diamondbacks Manager Kirk Gibson  will most likely try to get as man of his left handed bats (Adam Eaton , Jason Kubel , Didi Gregorius , Eric Chavez , Gerardo Parra , and Cliff Pennington ) into the lineup. Archer’s success will most likely depend on how he fares against this group.