Where has all of the Cardinals pitching depth gone?

There was a time, not so long ago, that the Cardinals were the envy of General Managers everywhere for their pitching depth.  You think your team has good pitching depth?  We had 3 guys who can throw 95+ mph (Shelby Miller, Joe Kelly and Trevor Rosenthal) vying for our 5th starter spot in 2013.

Now, with the expectation that Adam Wainwright will miss the rest of the season with an Achilles tendon injury, per Ken Rosenthal, the Cardinals pitching depth, or lack thereof, is going to come into question.

Gone are Joe Kelly (traded to Boston last year for John Lackey) and Shelby Miller (traded for Jason Heyward).  Rosenthal is the Cardinals closer and the pipeline of power arms seems to have dried up.

Now the Cards pitching depth consists of a bunch of lefty control specialists (Marco Gonzales, Tim Cooney and Tyler Lyons), while the team's remaining minor league power arms are either being groomed for relief (Sam Tuivailala) or are too far away from the majors to offer much help this year (Alex Reyes).

What is even more concerning is that, while he should have been groomed as a starter and allowed to build up his innings each year, Carlos Martinez spent the last two years in the Cardinals bullpen and, as a result, he will likely face an innings limit this year (speculated to be around 150 innings). 

Another concern is that Michael Wacha will likely be on a similar innings limit as well, after a stress fracture sidelined him for a few months last year. 

Assuming that Wainwright is out for the year and Martinez and Wacha reach their innings limits in mid-to-late August, who is going to step in to fill those voids?  Who will be in the Cardinals rotation in the playoffs?  Will they even make the playoffs?

These are legitimate concerns for a team that use to pride itself on its pitching depth.  What use to be a strength now appears to be a weakness and the team could suffer as a result.