Boost sires
That said Mike lets you know how a few of them might produce when he posts the yearly boost list. But other than that, it’s hard to tell how they might turn out. Try to pick sires that are bred by lines you do well with or you know do well in the sim. Horses that are by boosted sires or sires that do well in the sim I find do ok their first year.

Research
Another way is to go to the Bloodhorse stallion register http://www.bloodhorse.com/stallion-register/index.asp they show that year’s freshman sires and the price they are starting stud at. That can be an indication of how mike will rank the sire in the game. The more expensive the stud fee, likely better the offspring will be.

Then there is my favorite way to pick a freshman sire. A horse that you watched race and loved, when it retires breed it. Request For Parole, Graeme Hall, Peace Rules were all big favorites of mine. Peace Rules was horrible for me in the sim, but the other two produced well and were under-used. This is probably the most risky approach but hey if I like a sire in real life I really want one of his babies in the sim. Like Drosslemeyer: I love that horse. I cannot wait to use him in the sim.

Good DS and DDS do help
I am fortunate enough to have a good band of broodmares and I find it cheaper to breed freshman sires that are unproven to my good mares. There I no live data to show how the sire will do which is why you often see a sire that was a good runner produce really well for 2 years then when the real life babies come around and are not as good as predicted the stats fall. If you don’t have good mares, claim or buy in auction. Generally the better the DS breeding is the better chance the foal can run. This works well with the next method.

Waiting
A way to find out who is good and who is not is to wait. If you wait till June you get a small sampling of the freshman sires. Like Einstein, I used him right off the bat, I knew he was not your typically-bred sim sire but I liked him. In real life, he did well as a runner so I figured I would breed him. The baby has not broken her maiden but I think she will be better later but she has managed 4:0-3-0 in MSWs. Had I waited, I would have noticed what sire crosses worked best and if the win percentages were really worth the breeding points or credits. If you’re a more cautious breeder, this is the way to go.

All methods for determining a value of a freshman sire are hard, waiting till June is the most caution approach, and checking the stud fees allows you to try with a smidgen less risk. Breeding with freshman sires will almost always be a guessing game, but hey it’s why I like it.