Matt: I've added this to the front page because it's a great look a the breeding side of the game heading into the Belmont.
This is simple. It's about diversification of the Thoroughbred as a breed. An overly large number of sires' lineages right now have Mr. Prospector within a few generations. Many have him on both sides. He is a great sire and sire of sires. But there is a definite risk to concentrating on his specific bloodline to the overall variety of the horses out there.
So these are the Influential sires (roughly, not an exhaustive list) that are sired by Mr. Prospector (MP from now on):
Carson City (http://www.pedigreequery.com/carson+city) - Great Broodmare Sire.
E Dubai (http://www.pedigreequery.com/e+dubai)
Fappiano (http://www.pedigreequery.com/fappiano) - another Great Broodmare Sire
Fusaichi Pegasus (http://www.pedigreequery.com/fusaichi+pegasus) - 2010 #1 Stalllion by Progeny Earnings
Gone West (http://www.pedigreequery.com/gone+west) - Sired sires Mr. Greeley and Elusive Quality
Kingmambo (http://www.pedigreequery.com/kingmambo) - Progeny have earned 95 million
Miner's Mark (http://www.pedigreequery.com/miners+mark)
Seeking the Gold (http://www.pedigreequery.com/seeking+the+gold) - Stood for as much as 325k.
Smart Strike (http://www.pedigreequery.com/smart+strike) - Sired Curlin, enough said.
And the overall list of MP's progeny: http://www.pedigreequery.com/progeny/mr+prospector.
This is basically unreal. His production was out of this world. Absolutely unbelievable. But there is the risk that this HUUUUGE crop of sires (and their own sired sires, which I don't have the time to research and get into) will eventually limit the bloodlines that are truly influential in the thoroughbred community. Animal Kingdom has exactly zero in common with this family of sires.
If Animal Kingdom can make LEROIDESANIMAUX not just a legitimate stallion, but an influential one, that is nothing but good for horse racing. One of the major issues that industry commentators always bring up is that the thoroughbred has been bred so specifically that they are now fragile. Well, focusing on one major lineage certainly cannot help that problem.
If Animal Kingdom can win the Belmont (and I think he can and will) an infusion of (relatively) fresh blood into the overall community is a great thing. Yes, Animal Kingdom is Leroidesanimaux's only really big winner. Yes, who knows if Animal Kingdom will ever produce himself. Yes, it is only one stallion (or two with both of them) when contrasted with dozens that have MP lineage. But any new blood is a good thing for horse racing.
I know there are lots of ifs out there. But every bet you make at the track is a big if. It's no different on the back side.