"Pace Makes the Race" (Doc Sartin).
Pace can be a decisive factor anytime a contender controls at least two segments of a race.
Further, Early Speed as measured to the first call is not the same as Early Pace which is measured at the second call; in sprints, the former occurs at two furlongs and the later occurs at four furlongs.
They are two segments of a race, the first fraction and the second fraction; with the third segment being, the final fraction.
Accurate Pace figures based upon adjusted fractional times will answer important questions about how the race sets up.
For instance, whether front runners will be able to sustain the pace required to subdue all competitors, or if any horse will be in position to stalk the front runners and gain control during the late stages.
Pace study will also shed light on how interaction among front runners competing for the early lead is likely to affect the shape and outcome of the race, enabling handicappers to safely eliminate horses that do not meet the early pace requirements of a race, as well as, those that will not be in position to finish well based on running style.
Early Pace is best evaluated through the prism of the quality of the overall effort, in terms of finish position, margin of victory or defeat, lengths gained or lost in the stretch, and final time for the distance as adjusted by track variant (the speed figure).
Therefore, what's important is not how fast a horse can run to the second call but rather, handicappers want to know its comfort zone; how fast a horse can run to the second call, while turning in a winning effort.
Since more often than not, the faster a horse runs during the early stages of a race (the more energy expended); and the slower it will be running in the late stages (lacking energy for the stretch run); thus when challenged by another contender, a horse that is forced to run outside of its comfort zone during the early stages, will likely be fading in the stretch.