Britt Ghiroli published an article this afternoon about Zach Britton, with quotes from the pitcher saying that he won't be ready on Opening Day:
Personally, it would be tough for me to be ready to start the season. There's always that chance that you could be, but it's really hard for me to envision being ready for Opening Day, especially not facing Major League hitters or even going more than two innings [this spring]. Everything would have to go perfectly, so I don't think so.
Britton has been struggling with shoulder inflammation since last season, but he seemed to have been getting better before having another set back. The article goes on to say that they aren't sure what's wrong his shoulder to be causing the inflammation, which is frustrating. At least if something was visibly wrong they'd know their options.
As it is, Britton will probably start the season in extended spring training so that he doesn't have to rush back, and hopefully he won't have to spend time on the disabled list.
Taking Britton out of the running for the rotation narrows the field for the starting five when the Orioles break camp, and combined with other injuries it's starting to look like a good idea that they bought 452 potential starters into camp. Tommy Hunter has been struggling with a sore back, Tusyoshi Wade with a sore elbow, and meanwhile Alfredo Simon left yesterday's game with a pulled groin.
New Orioles Jason Hammel and Dana Eveland have both been healthy as far as we know, though I can't really get excited over the thought of watching Eveland every five days. Thankfully Wei-Yen Chen has been healthy and good so far, while Brian Matusz has been very good. It's too early to say that Matusz should be given a spot, although I do agree with Andrew's assessment from a few days ago.
It seems for now the only locks (baring any further injuries) are Hammel, Chen, and Jake Arrieta. We'll know more about Hunter later this week; he's scheduled to pitch Wednesday and if everything goes well, he could be ready for Opening Day. That's still only four pitchers, so it'll come down to Matusz, Eveland, and Wada (who has only pitched 2 innings this spring). I know who I'd rather see, and that's even with not allowing myself to be optimistic about Matusz.
Is Spring Training over yet?(Edited to correct Wada's injury. Thanks to the person in the comments who corrected me)