Here's what I do to handicap the Derby and what I look for in a Derby horse. One of the first things I do is narrow down the field to somewhere around 8 horses depending on the quality of the field. I really don't do anything final until I see how every horse takes to the CD track, obviously, it would be stupid not to, so really it comes down to the pp draw and then I make my final choices which is about 6 horses give or take depending on the field, same as you. But in terms of what I look for in a Derby horse, it is their pedigree, running style, their preps and my favorite thing to look for is who has a quick turn of foot with a nice, late kick (e.g. Afleet Alex and Street Sense).
I have found that those PFs and pace parameters are pretty accurate, too, no matter what people say about them. However, I dismiss horses who have a high PF in a sprint and then come out with a lower one in a route and that don't have the pedigree/running style like The Factor (even though he has the highest PF, he doesn't fit my profile - I didn't like him in the AD if you look at my comments on him before the AD), although he might not run anyway, but that's an example. The other horses with high PFs - Pants on Fire, Nehro, Dialed In, MMM, Shackleford and Archarcharch are fine because of either having the pedigree, running style and/or nice preps.
Another important thing I look at is a horse that is improving at the right time and who's figs go up with every start and added distance like Nehro and Midnight Interlude. Many will dismiss MI and in any other year I might do it to, but in this field he has a chance. But they will dismiss him because he just broke his maiden in March, but he is improving at the right time, his figs go up with every start and added distance, he has the pedigree (plenty of stamina from the bottom half with his dam winning at 9.5f and 11f and his bms at his best at or around 10f) and running style for the Derby, has Baffert as his trainer (a big plus with such a lightly raced horse!) and has a quick turn of foot which his sire and bms both had. Just watch the SA Derby again. He went 4w the 1st turn and then like 6w into the stretch. And most horses that would have to check up like he did, and so lightly raced, when coming to the wire would not come back that quick and pass up the horse they almost ran into and who had the momentum. It was very impressive and he should only improve off the 95 BSF and being so lightly raced. He is one to watch out for, trust me! My top 8 horses as of right now are: 1. Dialed In 2. Nehro 3. Mucho Macho Man 4. Midnight Interlude 5. Uncle Mo 6. Archarcharch 7. Pants On Fire and 8. Toby's Corner. But that could change depending on the works and post positions. Hopefully that helped a bit! I will get more detailed about each horse and the preps as we get closer and closer to the Derby! GOOD LUCK!