The Cubs haven't officially announced this yet, but there's apparently going to be a roster move Sunday:
Righthander Blake Parker joins the Cubs in DC— Judd Sirott (@Judd_Sirott) July 6, 2014
Here are some educated, but in the end, outright guesses about what's coming next. Chris Rusin, who joined the staff Saturday to bail out emergency starter Carlos Villanueva (who didn't find out he was starting until 11 a.m. Saturday), is likely headed back to Triple-A Iowa.
The Cubs are thus still playing with a 24-man roster, but that doesn't really matter until Jason Hammel's turn in the rotation comes up, which would be Wednesday in Cincinnati. Here's the current list of pitching matchups for the Reds series:
Monday: RHP Edwin Jackson (5-8, 4.99) vs. RHP Mike Leake (6-7, 3.47) Tuesday (first game): LHP Travis Wood (7-6, 4.62) vs. TBD or(8-6, 1.99) Tuesday (second game): LHP Tsuyoshi Wada (0-0, 0.00) vs. TBD or Johnny Cueto (8-6, 1.99) Wednesday: TBD vs. RHP Alfredo Simon (11-3, 2.78) Thursday: TBD vs. RHP Homer Bailey (8-5, 4.15)
So it'll be Wada who comes up via the 26th-man doubleheader rule to make his major-league debut. Then, one or possibly two more starters (Dallas Beeler? Kyle Hendricks?) will take Hammel's old spot in the rotation (Wednesday) and what was formerly Jeff Samardzija's spot (Thursday). At that point, I'd guess either Parker or another reliever (Justin Grimm, perhaps) will head back to Iowa.
None of this has been formally announced yet, but that's the way I see it given Judd Sirott's tweet and the rotation as shown above.