http://medford.craigslist.org/grd/1230457996.html
Here is a yearling filly who is starting her awkward, gawky stage and a perfect example of her buns being way higher than her withers. Her hoofies seem to be pretty level, even her back may be a scoche lower than her front and still her rear end is higher. Now her withers aren't really developed yet so it gives an impression of lower even than it is.
She's just a gawky girl, bless her bones! But all horses go through this. As she progresses through her second year, her front end and rear end will change heights pretty quick and you can see the difference in even as few as three days. But they don't seem to grow at the same time, it's like a ruler that one end is higher and then the other end is higher and so forth.
Since she's a Quarter Horse, she should pretty well level out when she matures. Her neck looks like it's jammed on instead of set on, this is normal too. Her neck is thin, that's normal. The thing I really don't like is the second pic that looks like she's looking around with her ears instead of her nose. I like 'em when the look at something with their nose sticking out first, that's what you see first instead of seeing eyes and ears first. Even from this angle, I think her head could be set on a bit better.
But this is a case of bloodlines. I wasn't going to check Allbreed but, in the end, I had to know, yep, I was right, she's a Hancock horse. So she's bred to work her buns off for you, not look purty and charm the socks off anyone. She'll be a working fool. So, for this, you can cut her slack on the weird way she's standing, especially that back near hock and the off-side leg.
All in all, I'll betcha she'll be a nice little horse someday. Thumbs up from me!