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. Or 180. Or perhaps even 160. Specifically, Rich Hill (last regular SP gig was in 2009), Jesse Hahn (170 IP the last two seasons...combined), Sean Manaea (74 IP last year, 122 IP the year before), and Henderson Alvarez (22 IP last year, then shoulder surgery), are likely to be capped at 140-160 IP -- and minor league innings count just as much as major league innings. Chris Bassitt and Kendall Graveman might be candidates to manage a slightly heavier load, but even Bassitt has never thrown more than 155 IP and that was last year when his season ended early due to shoulder soreness.
Perhaps Alvarez will not need any restrictions because his season, even including rehab, will naturally be shortened by at least a month. Hahn and Manaea, because they are pitching in the minors, might be pampered a bit with shorter outings than they would be asked to throw in the big leagues. Yet the reality remains that Oakland is likelier to have 5 good options healthy for the big league rotation than they are to have 5 good options fresh throughout the long season.
There is a solution to this, but it's probably too radical for the A's to do it. If they want guys like Hahn and Manaea, perhaps also Dillon Overton, to be fresh in August and September for the big league club, all they need to do is to shut them down for parts of the first half of the season. Every 10 innings Manaea does not pitch in May is 10 innings he will have in the tank in August. Every 3 starts Hahn skips in May is 3 starts he is fresh in September.
You know who can really relate to this dilemma? The Washington Nationals, whose decision not to start Stephen Strasburg's 2012 season late caused them to end his season early, quite possibly costing them a chance to get deep into the post-season.
As Hahn, Manaea and Overton use up bullets at AAA, Hill will be using his bullets in Oakland, Bassitt and Graveman will be reaching their own unchartered territory, and before long it will be August and all those guys will be, concurrently, hitting the same wall. And then what?
The A's could, and arguably should, find creative ways to stagger it (e.g., a late start to the season for Overton, a few starts skipped for Hahn and Manaea in May and June, skipping Hill's spot just before and after the All-Star break), so that come August and September, those guys are all not only ready to pitch in the big leagues but are also fresh enough to put their best foot -- and by foot I mean arm -- forward.
Unconventional? Yes. Yet the alternative is to have the majority of your key pitchers hit the wall at the same time -- the same wall where the writing has been all along.