Birdstone is like English Channel in that a savvy polo player or sponsor can pick up small, fast, sturdy and handy little horses at bargain basement prices, race them for fun if them want, and make good polo mounts when they're done racing.
Animal Kingdom -- went to stud in the wrong countries, full stop. France would have been a better option. With an average win distance of nearly 8f, and half his foals are 2yo, that says to me they want to run LOOOOOOOOOONG, which doesn't happen in the USA and isn't the main game in Australia, either. In France, he could have a go as a dual-purpose stallion.
Of the brigade of unproven stallions:
Frosted at $50k doesn't inspire. Yes, he ran lights-out in the Met Mile...and when he faced the top horses of his generation, he always came up short. Chrome handed Frosted his behind in the sandbox, he never got by Pharoah, he traded victories with Keen Ice. Arrogate plain old made him look slow. Even Shaman Ghost shook him off like a bad ex-boyfriend.
Tapizar is bred on the same cross, sired a monster filly in Monomy Girl, is doing a reasonable job so far, and stands for $10k.
Speaking of
Shaman Ghost, Stronach did him no favours by starting him out in California, even though he's from a deep old California family. Ghostzapper WAY upgraded the family, from listed class to multiple Gr-1 winner. He wasn't the most consistent winner, but he was consistently talented and IMO is priced appropriately at $7500.
As for
California Chrome, if his close and not-so-close relations are any indication, I think he will need a very specific cluster of bloodlines in his mares: as much Commando as he can get...Sir Ivor, Bloodroot (Lalun, Bimelette, Never Bend, No Robbery), Tom Fool (Tim Tam, Buckpasser, Buckaroo, Jester), Deputy Minister (Awesome Again, Dehere, Touch Gold, Forest Camp, Silver Deputy), the Ciboulette family, and especially Dehere, Meadowlake, Ghostzapper, and Hold Your Peace...and it needs to be mares with genuine speed. If he gets that type of mare, he'll probably be fine. Will he get them? Maybe. At $35k he's a big risk but given that he had talent and his full siblings are showing talent, probably less of a risk than...
Arrogate at $75,000 and
Liam's Map at $20,000. (There, I said it. Fight me.

) So far, Unbridled's Song has a pretty poor record as a sire of sires, with his two most consistent sons being Midshipman (standing for $8500) and Even the Score. With sons of dams like Take Charge Lady, a Gr-1 winning daughter of Toussaud, a Gr-1 winning half sister to a BC Distaff winner, and the dam of Honor Code all either sold overseas or off to a super-slow start, it's hard to see how the sons of a multiple Gr-3 winning mare who traces to Ta Wee and a listed stakes winning mare whose 2nd dam is Meadow Star will be any different. Arrogate is especially risky at that fee, particularly given that you can get Candy Ride, More Than Ready, or Speightstown for $5000 more.
And now the cat is telling me it's time to go to bed so I'm going to listen to her.