^ Fluke doesn't mean we should assume every slightly talented horse will produce the same.
Breeding is about genetics, genetics is science, there are no flukes, only things that we don't understand, and what we don't understand is huge compared to what we do. Breeding is done based on a whole slew of assumptions which may or may not be correct.
Her pastern and hoof angle do not match...the pastern is more angled than the hoof. Now this could be due to needing more off the heel and toe, but if she's already a size 0 shoe, I'm not sure how much more you can take off.
Is she desperately weak in the pastern, though? No not yet...but the potential IS there; make for darn sure you always keep her feet in good condition...especially keep her toes from getting too long, as that is only going to add more strain on those pasterns.
NOOOOOOOO! Very short pasterns are IMO a bigger issue than somewhat long pasterns, both for soundness and for riding comfort. Plus, breeding short to long does not usually equal medium, which is the most correct-- IMO, the OP would be best off using a stallion with the most correct pasterns if they choose to breed their mare.