It hasn’t been a problem before.
There’s a better view of the race from ESPN
http://espn.go.com/video/clip?id=4128506&categoryid=2488837
You just haven't noticed. They might isolate on six horses or so; and if they don't have the right one they might be able to cobble together a video which makes it seem as if they did. Mine That Bird was way behind the 2nd last horse through the first 3/4 mile. He wasn't in any of the close-ups they took for at least the first 60% of the race.
There’s a better view of the race from ESPN
This "better view" is just the ordinary track feed; and you're right, it is a better view. It is disgraceful that the Network producers think they have to improve on something that they really don't have much knowledge of. The reason the track feed works well is that it is shot from only one fixed perspective, which is the same number of perspectives you get if you watch a race live. Viewing a race from a camera that is moving with the horses is unnatural and confusing unless maybe you are a retired jockey; and switching from head-ons to pans (A pan shot is the track feed style.) makes it difficult to continue following a single horse or group of horses. (I have similar feelings about the flying cameras now used for football. The show you what it would look like to a bird; but since none of us are birds it doesn't work.)
ML/NJ