Let me start this off by saying that I'm incredibly hopefully I'm not putting the cart in front of the horse here. As things stand, Minnesota is on the outside looking in, and trails both the Houston Astros and Texas Rangers. With the Los Angeles Angels not far behind, things will get interesting before they get sorted out. For argument's sake though, let's assume that the Twins are your second AL Wild Card team.
Rather than simply breaking down who starts a one game Wild Card contest for the Twins, I want to take things a step further. Should the Twins need a win and in situation (a game 163), or maybe they advance to the ALDS, here's how I would urge manager Paul Molitor to handle things on the bump.
Game 163
If the Twins keep going at the rate they are, separation isn't something that appears to be on the horizon. Minnesota has been jockeying with the AL West for most of the second half, and that's where they'd find a game 163 opponent. Minnesota owns a 1-2 record against the Angels, 3-3 versus the Astros, and 3-3 against the Rangers. Whoever the competitor is, there's only one man for the mound.
With a game 163 falling into the regular season category, PED-user Ervin Santana would be eligible to pitch in the game. The argument for who gets the ball should begin and end with Santana. Not eligible for the postseason, Minnesota utilizing their 2015 free agent signee in his final capacity is a must. There have been some rocky outings, but in his last 3 starts, Santana has been lights out. His 1.23 ERA and 27/4 K/BB ratio should play healthily towards helping the Twins advance. Allowing just a .228/.282/.304 slash line, Santana has continued to have the upper hand on opposing batters.
If Minnesota needs to get just one more win, the $55 million man in Santana is my choice.
AL Wild Card
Major League Baseball introduced the second wild card team recently, and in doing so have created a one game first round. With a full rotation not yet needed to be considered, the wild card game is another must win situation. The Yankees seem to be the likely team awaiting its opposition, but the Blue Jays could find themselves in the contest as well.
Despite ugly starts for Kyle Gibson against the Yankees (10.72 ERA across 5 starts), he's absolutely who I go with either way. Gibson has been one of Minnesota's best starters (if not the best) this season, and he's rolling off late (2.45 ERA since Aug 22). On the year, Gibson has added nearly a full strikeout to his career best 6.3 K/9, and he's walking batters at a career low 2.9 BB/9. On pace to push towards 200 innings, Gibson has been a horse for the Twins.
Not just a by-product of Santana's ineligibility and rotation uncertainty, Gibson is who I trust to start the playoffs.
Playoff Rotation
Under the assumption that the Twins and Molitor would look to utilize a traditional three-man rotation, we have two spots yet to decide. Gibson getting the ball for game one, the discussion would be between Mike Pelfrey, Tyler Duffey, Phil Hughes and Tommy Milone.
Of the three candidates, Milone is a lock for me. He's had a strong year pitching to the tune of a respectable 3.73 ERA. Owning a 3.67 ERA since his recall (Aug 16), and owning a 3.06 ERA in September, Milone is peaking at the right time. His low walk rate should spare him trouble, and giving the Twins a chance to win remains the ultimate goal.
Selecting a third starter, and a guy that I might start in front of Milone, would be Phil Hughes. Last season's ace, Hughes has been a different animal this time around. The home run problem has plagued him in 2015, and September is the only month in which he's yet to surrender a long ball (having made just one start). Hughes is still settling back in after a DL stint, and while he's capable of being a go to, the big run innings provide a level of uncertainty in the playoffs. Under different circumstances, I'd feel more confident about Hughes. Nonetheless, he's another lock for inclusion in the rotation.
Going with Gibson, Milone, and Hughes leaves both Pelfrey on the outside looking in. I think both pitchers can be very effective out of the bullpen (a role I think Duffey finds himself in during 2016). Pelfrey is going to pitch in long relief in the playoffs almost assuredly, but Duffey may not find himself on the 25. I'd keep Duffey over a bench bat, but that's another discussion.
At the end of the day (er September), we'll have a better idea if this discussion even matters. Should the Twins find themselves in one of these three positions though, these are the pitching situations I think the best playoff opportunity evolves from.