We know the pitching is a problem, but I'm going to try to dive into the numbers and pinpoint what the exact problem is.  Reference links at the bottom of the post.

K/9: 7.01 (14th in MLB, 5th in AL)

Our strikeout leader is...Adam Eaton.  Guts and Koji have a K rate in the 5's, which isn't very good at all, and Ray is at 11.  Overall, respectable.  This may be the low point between Bedard and Good Danny, and the Cavalry we are continuously being promised.  For now, if our two main starters could miss a few more bats, we'd be in much better shape.  More on that in a bit.

BB/9: 3.25 (4th in MLB)

How weird is that?  Our spare parts pitching staff has division-best control.  I think getting rid of Death Cab dropped that by at least two points.  Capt Kirk keeps telling them to throw strikes, and they're actually doing it now. 

HR/9: 1.86 (29)

Giving up more HR than everyone but the Phils...of course, Simon with his videogame-like 7.11 HR/9 won't be back, and Bass seems to have gotten it out of his system, at least for a while, our bright spot here is...Adam Eaton (2 in 21.1IP).  Guts/Koji have each given up 5, that tall lefty has served up 7 meatballs, and I haven't even mentioned Fly Ball Sherril, as he hasn't gotten started yet.  We need to work on this.  Badly.

WHIP: 1.63 (30)

So how can we be so stingy with free passes and have the highest WHIP in the bigs?  We let them hit the ball.  A lot.  Why take a walk when you can hit a hanging curveball or an 88 mph fastball to Pie or Wigginton or to a fan out in the bleachers? 

Opponents are hitting .308 against us, highest in the majors. SLG is an ugly .541, thanks to 40 HR and 58 2B.  The second worst SLG in the AL is CLE with .485.  It's like everyone we face turns into a team full of Ryan Brauns, except for Ian Kinsler, who would probably take a pay cut to face us more often.

Our current rotation (H/9): Guts (11.1) KOJI (8.4) Handu (12.8) Bergy (13.0) Eaton (12.2).  One of these things is not like the other. One of these things is acceptable.   The number of hits we give up is so bad that it's turning our advanced defensive statistics into a statistical anomaly.  We're rated last here, but we know that's not true, with certain exceptions.  Don't get me started on defensive stats.

GB% (MLB avg: 43.3%):  Guthrie (30.3), Eaton (29.0), and Uehara (23.9) are sub-poor to poor here.  Bergesen is a rock start here with 61.1%, and Baez and Bass are also above 50%, probably Bass's saving throw.

FB% (MLB avg: 28.4%): Guthrie (51.5%), Uehara (58.8%), Hendrickson (46.4%), Eaton (47.8%).  See the problem?  Sherril (51.5%) is our closer.  Bergy, JJ, Bass, and Baez are the only pitchers below average here.

Summary: When we're pitching, we're throwing strikes that batters like to hit.  We need to get the ball down and past the hitters.  Relying on the defense is great to an extent, but we're overworking the defense, and the opposition is exploiting the weak points.

Our rotation and our bullpen are about the same overall.  The bullpen is the most overworked in the majors, but if you didn't see that coming, you don't know much about baseball and pitching and the Orioles.  I don't think that's a bad thing, as we have lots of guys ready and willing and semi-able to do the job, and while we need our starters to last longer, we need to plan for them not to.

One thing I'm wondering about, and that's if the way we dealt with pitching in ST (bringing 37 guys in and letting them all fight it out) didn't set us back in the development department.  By not focusing on the important guys (since we didn't know who they were going to be for the most part) I wonder if we didn't give them enough opportunity to build up per a plan.  Guts in the WBC was probably a bad idea, and his early struggles hopefully stay early.  Simon probably got hurt puching himself too hard too early.  Bass was a nightmare early but he seems to be in a groove lately.  Koji is climbing his learning curve, Bergy will probably have fits and starts and pitch a couple of gems and get hammered a bit.  Eaton will be crappy and pretty good.  By now everyone should be ready to be competitive, at least conditioning wise.  Winter is now behind us and we need to work on getting velocity up and pitches down.  We actually have a fighting chance to be a decent team if we can do that. 

References:

Fangraphs

Baseball Reference

Stat Corner

Stat Corner Glossary