Who will be our designated hitter for interleague play on the road? I've got two candidates in mind: David Ross, Eric Hinske, or Joe Mather. We will obviously be playing with a 4-man bench, so Fredi will have to think clearly about who will be the hitter, and where they will be in the lineup.
I would want them to split time while playing. The way you'd do this is by basing it on who the pitcher is. For righties, the choice is hard. Eric Hinske has an OBP of .362 and a SLG percentage of.614. He is hitting .341 (15-44) against righties this year, with 3 of his 4 homers and 10 of his 11 RBI against righties. His wOBA is .418 in 47 plate appearances. David Ross, on the other hand, is also hitting well. Ross has an OBP of .435 and a SLG percentage of .864 against righties. He is hitting .409 (9-22) against righties with all of his 3 homers and 7 of his 9 RBI. His wOBA is .557 in 23 plate appearances. For Joe Mather, he is 1-5 with 3 strikeouts, with an wOBA of .179. I'm going with Eric Hinske in this one.
Then there are the splits for playing against southpaws. Eric Hinske has 1 hit in 7 at-bats, a SLG percentage of .571 and a OBP of .143 (the same as his batting average), and an wOBA of .302. He has 1 homer and 1 RBI in this split. For David Ross, the numbers aren't any better. He's 1-9 against southpaws, and a .125 SLG percentage and a .177 wOBA. For Joe Mather, hitting against southpaws has been better. He is 3-11 with 3 doubles and 4 strikeouts. He has an wOBA of .378 and an OBP of .333, and a SLG percentage of .545. I'm not too sure about who to go with in this one.
I'm really thinking that Eric Hinske would play well against the American League, knowing that he's hit against the American League pitchers when he was with New York, Toronto, and Tampa Bay. In Hinske's career, he's hit .225 against southpaws, and .262 against righties. He sports a career .346 wOBA,.305 BABIP, and a .194 ISO against righties, and a .301 wOBA, .274 BABIP, and .160 ISO against southpaws. Then again, David Ross could really be a powerhouse as he's been so far. Ross has a .230 average, .331 wOBA, .269 BABIP, and a .218 ISO against righties. He has a .244 average, .334 wOBA, .289 BABIP, and a .211 ISO against lefties. This graph from FanGraphs shows Hinske's career ISO. Note that Hinske played in the American League through 2009.
The following graph compares the wOBA of Eric Hinske, David Ross, and Joe Mather. Click to enlarge.
After all this, my opinion is to have Hinske playing against righties, and to have Ross play against lefties.