Like many other angles, it may or may not mean something. I like to see a well bred expensive horse that maybe didn't do to well as a 2 yr old have a few starts as a 3yr old and suddenly show improvement in a race , but not win it. It can be an indication that whatever problems the horse was having are now over and that the horse may start reaching it's potential. It, of course , is only one factor. In general, a horse who costs let's say $200,000 as a yearling is not going to a trainer who is a doofuss. You can assume the horse has received proper nutrition and medical attention. I know some owners and trainers look for well bred horses not doing well to get them cheap and maybe turn them around. This is not like claiming a horse and taking 2-3 seconds or more off it's time in a few weeks. It may take many moths or even a year or two to get the results you expect, You have to have a good feel about when you might use that angle. You would go broke just betting the most expensive yearling in a race.