The Belmont has been a very difficult race to unravel during the last decade. At first glance it seems as if inferior horses win this race all the time. Da' Tara, Birdstone, Sarava and Commendable are horses that some people can't even figure out years after the race.
In my own handicapping I've noticed a propensity to focus on the factors that I traditionally consider relevant. Stuff like speed, current form and race condition preferences. Unfortunately I usually lose because it seems as if the Belmont is less about those things and more about the fitness of the individual.
Fitness can be measured in many different ways. For the Derby the focus of fitness statistics is based on determining whether or not a horse has built up enough fitness to withstand the rigors of 10f. For the Belmont the focus shifts towards determining whether or not a horse still has enough left in the tank to go 12f. Many times the Triple Crown trail has left some of these horses jaded even if they weren't entrants in the Derby and Preakness.
From the year 2000 to the present there has been 85 starters in the Belmont. 21 of them entered the race having more than 5 races since their last layoff and none of them wound up as winners. They compiled a record of 21-0-2-2. Notable horses like War Emblem, Monarchos, Perfect Drift and Hard Spun were among them.
Even a normally positive angle like a bullet in their last workout could wind up being a negative. Horses with a last work bullet in the Derby have done extremely well but in the Belmont they're 17-2-0-1. The only horses that managed to run a bullet and still win were Afleet Alex and Point Given. Perhaps not coincidentally, they were also the most formful winners of the last decade. Others like Big Brown, Funny Cide, Perfect Drift and Bob and John were not able to achieve Belmont success after fast final workouts.
Normally I advise to simply play the big races like you play any other race but for the Belmont it's worth remembering that for a variety of reasons it's unlike most other stakes races. The keys to victory seem to be more about fitness and experience than speed, class or form. If you're anything like me speed, class and form are usually the first things you focus on.