Two days ago, the Athletics were forced to put lefty Sean Manaea on the disabled list due to a shoulder impingement. On Tuesday, the rotation was dealt another blow: 

Given that these are arm injuries, a quick return for either would be pretty surprising. Anderson's injury history doesn't bode well for the situation, either. 

Anderson, 30, is 3-4 with a 4.02 ERA (102 ERA+) in 65 innings this season. He had a 3.47 ERA before a terrible outing in Houston Monday night. The issue here is less losing an ace and more losing someone capable to giving them 5-7 quality innings, which Anderson has done several times. 

The A's have already acquired a starter this month in Mike Fiers. They probably need to grab another one in addition to putting Daniel Mengden back in the rotation. A Gio Gonzalez reunion would make sense, but the A's might be done making any major moves before the Aug. 31 waiver trade deadline. 

Despite using a bit of a patchwork rotation for much of the season -- Edwin Jackson and Trevor Cahill remain in the rotation, after all -- the A's have gotten good work from their starters for several weeks. A's starters have a 3.32 ERA in the second half and it's down to 2.72 in August. 

For now, the rotation looks to be Fiers, Jackson, Cahill, Mengden and TBA. 

Looks like club president Billy Beane and general manager David Forst will need to pull another rabbit out of a hat as the A's pursue the Astros for the AL West title.