Babe Ruth cards: 1932 US Caramel vs. 1933 Goudey

When it comes to card collecting, there are some general rules of thumb that tend to hold (all else equal...or ceteris paribus for the econ geeks).

1. Old cards are more valuable than new cards
2. Scarce cards are more valuable than abundant cards
3. Cards in good condition are more valuable than cards in poor condition

There are other factors (including aesthetics), but, in most cases, those rules tend to hold.

So why is it that Babe Ruth's 1932 US Caramel card isn't worth significantly more than his Goudey cards?  The US Caramel card is older AND more scarce.  We can control for condition.

There are 128 US Caramels graded by PSA and the recent average value of PSA 3 transactions is $3900:

By contrast, PSA has graded almost 900 red Goudey Ruth #149 cards.  900!  And the recent average value of PSA 3 transactions is $3700.

Let me summarize.  There are 128 PSA graded 1932 US Caramel Babe Ruth cards and the PSA 3 version is trading at $3900.  There are almost 900 PSA graded 1933 Goudey Babe Ruth #149 cards and the PSA 3 version is trading at $3700.

There are 750 fewer US Caramel cards and they are only trading for 5-6% more?

I think there are two possible explanations - and both could be happening simultaneously.  One, mainstream media has driven up the prices of the Goudey cards given the importance of the set - after all, there are many stars, including four of Babe Ruth.  Two, the US Caramel cards are relatively undervalued.

What do you think?