He had a few good runners, nothing that matched him of course but then only one sire can claim to have produced such quality and that is Secretariat's sire. Overall Secretariat was a decent sire but nothing special. His most notable baby was Lady's Secret who was a Breeder's Cup winner and Horse of the Year (and I had the great honor of working with her for a few months while night watching on the farm she lived her last few years on) a couple of his other very good babies were Risen Star and Tinner's Way. Secretariat was much more well known as a broodmare sire, his daughters were pretty good producers, they produced such superstars as Storm Cat (out of Secretariat's daughter Terlingua) and Gone West (out of Secretamme). His daughter Weekend Surprise in addition to being a stakes winner herself had a couple of major winners who were also very good sires, I just can't remember the names off the top of my head, AP Indy might be one of them? Interestingly as well is that his daughters had very good colts who went on to be very good sires, the above listed are all extremely important modern sires.
Overall his numbers actually were pretty decent, he sired 653 foals, 488(75%) of them made it to the racetrack and 328(67% of starters, 50% of foals) were winners.