Perhaps no rotation in baseball has been more ravaged with injuries than the Oakland Athletics this season and here's another blow. Southpaw Sean Manaea has been down since late August with a left shoulder impingement, but now the A's have announced that he'll undergo arthroscopic surgery on his shoulder. He could be out through the 2019 season:

Manaea, 26, finishes his third MLB season 12-9 with a 3.59 ERA, 1.08 WHIP and 108 strikeouts in 160 2/3 innings. He threw a no-hitter back on April 21 and is arguably the most talented pitcher the A's had on their roster this season. 

Moving forward, the A's rotation looks like so: 

  1. RHP Mike Fiers
  2. RHP Trevor Cahill
  3. RHP Daniel Mengden
  4. RHP Chris Bassitt
  5. RHP Edwin Jackson

It's patchwork, to say the least. Only Mengden was on the opening-day roster. And yet, the A's are 87-57, in playoff position and within striking range of the AL West title. 

The injuries to the pitching staff started back in the spring. All told this year, the A's have had Kendall Graveman, Daniel Gossett and Jharel Cotton undergo Tommy John surgery. Manaea now needs shoulder surgery. Andrew Triggs has a nerve issue in his arm. Paul Blackburn has an elbow injury. Brett Anderson has a forearm injury. 

Still, the A's have gotten quality work from unlikely sources and outside additions. 

  • Jackson hadn't been a productive starter since 2011. He was released by the Nationals on June 1 and the A's added him June 6. He's pitched to a 3.26 ERA in 14 starts. 
  • Cahill hadn't been a productive starter since 2012. He signed a minor-league deal in mid-March. He's now pitched to a 3.77 ERA in 19 starts. 
  • Anderson had a 7.29 ERA in 66 2/3 innings in 2016-17. He gave the A's a 103 ERA+ in 13 starts. 
  • The A's got Fiers for a Double-A reliever named Nolan Blackwood in August. Fiers has been excellent since. 

What the A's have done this season is amazing for many reasons, but perhaps the most remarkable is what they've gotten from their patchwork rotation in light of all the injuries.