FPDW, Another "Why" regarding Draws

[StrayBullet]

I hope this isn't too stupid of a newbie question, but I really have a need to understand the "why" behind the most ev moves.  If it makes sense to me, then it's more likely that I'll recall it when I need to

 
Playing the FPDW trainer from Bob Dancer:
 
4s 5s 6s 5h 2s, the optimum play is to hold 5s 5h 2s
 
yet for:
 
5s 6s 7s 5h 2s, the optimum play is to draw to the oesf.
 
Why?  From what I can see, the outs are the same on the high and low ends...what am I missing that's STARING me in the face?

[shadowman]

More straights and SFs with the 457W. When you go below the 7 you run into cases where the deuce is interference with the other cards. When you have questions like these a good approach is to look at the analyze hand function and look over the results from each hand.

[StrayBullet]

Appreciate the quick response, thanks!
 
I have looked throuh the Analyzer, but maybe I'm not reading/comprhending the information correctly.  Too bad it doesn't have a text box to explain , or more accuratley, summarize the data so readers can understand why the move is made.
 
In this example though, I still don't see how 456w has more outs than 345w...but I'm still open to being bashed across the head with a hammer

[shadowman]

If you think of the deuces as jokers and the deuces as missing cards it helps clear this up. You still have 52 cards and everything is equivalent. Clearly, the lower the cards you are holding the fewer straights and SFs can be made without any deuces to draw to. Once your highest card you are holding is a seven (567) then the deuces no longer effect the possible winning hands. With 456 you lose a few winners and with 345 you lose a few more. These can be seen when you scroll over the number of each type of winning result using the analyze feature.

[StrayBullet]

That's the bashing over the head I was looking for, thanks!

[shadowman]

We all had to learn this sometime. The missing 2's in this case is the equivalent of what's called penalty cards. Cards you throw away and cannot be drawn that could help the hand if they were still in the deck.