I was recently analysing some results and in the sample I came across an above average win strike rate group of horses. They were all lightly raced (<= 4 starts) resuming from a spell. Why is a horse spelled after only a few starts? More education, recover from injury, more growing up, who knows, but they win more than their fare share of races, upon return from that spell.

Do yourself a favour and research it, there are some profitable niches.