After his last outing of only 4 innings against the Red Sox and his ERA hovering near 7., Yost informed Carlos Villanueva he would be removed from the #4 starter role. Lucky for Villa, we have Seth McClung to take on that role and Carlos can stay with the big league club as a long reliever. 

However, if this switch doesn't work out and McClung struggles as well, expect to see Jeff Weaver brought up from AAA.

What I find funny in all this is the double-standard Ned Yost manages by. He refuses to shift the batting order around and move struggling players (Weeks, Cameron, Hall, etc.) because he wants to maintain consistent roles for his guys. On the other hand, our pitching is an absolute chaotic mess of constant shifting, demotion, promotion, etc.: 
Bush was sent to minors then recalled when Gallardo got hurt (again)
Turnbow was sent to minors to find himself and Joe Dillon got recalled
Gagne was removed from closer's role and re-installed a day & a half later. Mota blew one in his absence.
David Riske got hurt and Mike DeFelice was promoted from minors (after 10 years with no big league experience)
Mitch Stetter forgot how to throw stikes, was demoted and Zach Jackson was called up (Additional note on Jackson: he was a starter in Spring Training and AAA but is now a long reliever).
And McClung switched spots with Villanueva for our #4 starting role.

And, we've only played 45 games, with this much pitching turmoil. Yet Rickie Weeks stays as our lead-off man?! We've got 3 every day starters batting below .200 = Weeks, Cameron and Hall and 2 starters below .240 = Fielder and Hardy. Our core of Braun, Hart and Kendall cannot sustain us. Thus, LAST PLACE.