News broke before today’s A’s game that Mike Sweeney will have arthroscopic surgery Wednesday to repair cartilage in his left knee. It’s not a complete shock, but still an obvious blow to the A’s offense. Sweeney said his knee just hasn’t responded to treatment, and it didn’t feel right after he tried taking batting practice Saturday.

The plan is for Sweeney to rehab in San Diego for about two weeks with a therapist he worked with last season, when he had surgery on his right knee while still with Kansas City. Sweeney said he’s been told that the best-case scenario has him resuming baseball activity in three to four weeks. The standard time frame for return from this procedure is the 4-6 week range.

So what does this mean for the A’s? It means they’ll be watching Frank Thomas’ recovery even more closely. This  offense  has a tendency to fall silent for extended stretches, and being without two of their most productive bats for a prolonged period isn’t encouraging. Thomas will stay in Las Vegas treating his injured right quad for about another week, before returning to the A’s and starting to hit.

Considering Sweeney’s comments before the game, it’s no wonder he’s considered such a great clubhouse guy.

“It breaks my heart because I’m not going to be with my team,” he said. “It’s a team I’ve come to love since spring training. We’re so close to playing amazing baseball and getting close to the top of the standings.”