I'm actually comfortable with the A's starting pitching depth right now. The current starting 5 (Sonny Gray, Rich Hill, Chris Bassitt, Kendall Graveman, Erik Surkamp) may not be world-beaters, but they are really just holding down the fort until Jesse Hahn, Henderson Alvarez, and Sean Manaea are ready and that could easily be as soon as late April, late May, and mid-June, respectively. This is a good rotation that figures only to get better with each move.
Here's the rub. Several of these key pitchers are unlikely to be able to throw 200 innings.