The kick plate conceivably allows the rear leg to produce more force and generate higher horizontal velocities than can be developed with a track start on a traditional block.
The benefits of an effective start in competitive swimming cannot be underestimated. Evidence from race analyses conducted at major international competitions demonstrates significant correlations between faster start times and race times (Cossor and Mason 2001; Mason, Alcock, and Fowlie 2007).
The start produces the fastest velocity that a swimmer will achieve during a race. When you consider that the start includes the first 15 meters of the race, it makes up a considerable proportion of the total event, especially in the shorter sprints over 50 to 100 meters (figure 6.1). Swim starts as a percentage of the race distance (start distance is 15 meters).