Why are the Cards/Rams afraid of depth?

The Cards lost again today... they have now lost 2 series' in a row, to two very mediocre teams (Cubs, Brewers). The achilles' heel for the Cards (once again) is a pathetic effort by the offense. Which begs fans to revisit the question: 'why did we trade Ryan Ludwick?'.

I realize that the back-end of the rotation was/is a big question mark. Lohse has been pathetic this year, just like he was in '09; and it is unknown whether or not Penny will be pitching like himself when he returns. But even with the questions surrounding the #4 and #5 spots in the rotation, the rotation still has not lost as many games for the Cards as their offense.

Ludwick was our 3rd best player, behind only Pujols and Holliday. And he was our best hitter with runners in scoring position. So the Cards decided to trade him, despite the offensive struggles. And despite Ludwick being our 3rd best player, we still did not get Roy Oswalt, and we did not get Dan Haren; both pitchers were available for trade. Instead, we traded Ludwick for a very average Jake Westbrook. 

One reason for this trade was that our outfield was supposedly crowded with Ludwick, Colby Rasmus, Matt Holliday, Jon Jay, and Allen Craig. So the Front Office was willing to part with Ludwick because of that depth. But unfortunately, Ludwick was the reason for that depth. Today we saw what little depth we actually have. Rasmus was out with an injury, so we had: Holliday, Jay, and Craig in the outfield. So now our depth relies on Allen Craig, who is hitting .161. I would say that we should end the Allen Craig experiment; because the guy is only known for one good series against the Dodgers, and has literally done nothing else. But we can't end the Craig experiment now, because he is all that we have for depth (unless you want to get excited about Stavinoha or Winn).  So we basically lost our depth in the outfield, in exchange for a mediocre pitcher that might lead us to one or two wins total on his own.

Unfortunately, the Cards are not the only team in St.Louis that does not value depth. The Ludwick situation is somewhat similar to the Alex Barron situation with the Rams. I know Barron was frustrating to watch, and that he is as dumb as a rock. But the truth is, he has been the only offensive lineman capable of staying healthy for 16 games. I'm not saying Barron should have been a starter for us this year, but I do think that having a durable back-up OT with NFL starting experience (just incase Jason Smith or Roger Saffold get injured) is more valuable than OLB Bobby Carpenter (the player we traded Barron for). Carpenter might not even make the team, so we basically traded our emergency OT for possibly nothing.