The ability to defeat rival competitors in any circumstance, to overcome disadvantage and setback.
Poor start, pace duel, wide trip, shuffled, bumped, forced to steady, a wall of horses, whatever; any horse that holds a meaningful Class advantage, true Thoroughbred Class, will do whatever is asked.
The challenge then for horse players in terms of Class, would be to ascertain how a race horse compares against each of its competitors; but this can be blurred by the varied levels, conditions and restrictions in horse racing, and further complicated by any number of different trainer maneuvers which are unfolding at every racetrack on race day.
While every thoroughbred horse race presents a unique set of challenges to the entrants, the winning horse will combine the three elements of class more effectively than its competitors.
Demonstrating the required mix of Speed, Determination and Stamina to "outclass" the field and prevail on this day.
Moreover, we view Class as sharing an interdependent relationship with every other [handicapping] factor; forming a dynamically changing interweave which will become the horse's ultimate expression of its Class on race day.
We approach the difficult task of discerning Thoroughbred Class by understanding first, that it's the most important Primary Handicapping Factor, since by nature true Class will possess inherent talent to overcome Speed or Pace advantage, a troubled trip, or whatever.
Postulate: A thoroughbred's "True Class Today" (the mix of speed, determination and stamina the horse will demonstrate today) will be a combined function of its Breeding, Speed, ability to sustain a Pace and Current Form; as influenced by Secondary and Unknown Handicapping Factors.