Now that Jason Hammel and Jeff Samardzija are officially part of the Oakland Athletics organization, the A's need to make a pair of moves to clear two spots on the 25-man roster. One is fairly obvious — though he's pitched well in Oakland, Brad Mills was never a part of Billy Beane's long-term plan for the starting rotation, and he'll be optioned.
But that leaves Oakland with six productive, big league-caliber starters: Jesse Chavez, Tommy Milone, Sonny Gray, and Scott Kazmir, plus Hammel and Samardzija. One of the first four will have to be sent down (or, less likely, accept a role in long relief). It seems safe to say that it won't be Gray or Kazmir, as both of them have put together first halves worthy of All-Star recognition. So the conversation is one between Milone and Chavez, both of whom have exceeded expectations in 2014.
There is a slight possibility that the front office has had its fill of Jim Johnson, and is interested in relegating Chavez to a long relief/jack of all trades role in the bullpen. He could take Johnson's roster spot, giving Hammel and Samardzija two spots to claim when they get to Oakland. That seems like a stretch, though, and it's likely best to limit the conversation to which starters will go where.
Milone, despite larger ERA fluctuations, has been fairly consistent throughout the season wOBA-wise — he's hovered between .301 and .341 in wOBA-against, with the .341 coming in June. Milone has also pitched best at home, with a 3.12 ERA at the Coliseum this year as compared to a 4.40 in road ballparks.
Then there's Chavez, who was unhittable (.242 wOBA) in April, very hittable (.354) in May, and much better (.294) in June. The issue with Chavez, though, is that he has already thrown more innings than he ever has at the Major-League level, and almost as many as he's thrown in any season in professional baseball. But Chavez's June numbers show few signs of fatigue. All the same, counting on a pitcher who has typically maxed out at 120 innings per year and is already at 103 seems risky at best.
In the end, my feeling is that Chavez is likely the odd man out, not because he's objectively not as good as Milone but because he doesn't have a full MLB season under his belt. His demotion would be very much short-term, and Oakland's phenomenal starting depth would allow Beane and Bob Melvin to give their other starters of questionable endurance (Sonny Gray, for instance) an occasional stint on the DL, or just a skipped start, to keep them fresh down the stretch.
Obviously, somebody else is going to get injured at some point; suffice it to say that finding spot starters will no longer be a concern.
Now, throw in the last wrinkle: Drew Pomeranz. After breaking his hand on a clubhouse chair following his worst start of the season, Pomeranz can't be much of a darling in the eyes of Oakland's front office. All the same, he was incredibly productive in his eight starts this season, sporting an overall ERA (including relief appearances) of 2.91. Pomeranz could easily slot back into a relief role, or simply continue to develop and provide depth at Triple-A Sacramento.
There's also the very realistic possibility of Billy Beane using his newfound glut of starting pitching to go after what most consider the final weakness on this team: a true second baseman. That topic is worth a post of its own, but Beane certainly has the trade chips and the roster flexibility. He could also use the pitching to restock a very depleted farm system after this season — seems like the A's might be in need of a shortstop more MLB-ready than Daniel Robertson.
Brad Mills was scheduled to pitch Sunday, and Samardzija was scheduled to pitch tomorrow (Saturday). If you want to see an A's debut, it seems safe to buy tickets for the 1:05pm matinee to close the four-game set against Toronto.