Ask a scout to define “explosive” and he'll likely have a difficult time explicitly defining it. He’ll say “twitch,” he’ll say “juice,” he’ll say “violent” and he’ll obviously be right, but that's been part of the problem for much of the history of the sport. For most of the history of this sport, explosiveness was a feeling and a subjective eye test measure. Which, for conversation's sake, is totally fine. You knew it when you saw it and you struggled like hell to write it down, or perhaps compare one player's explosiveness to another's.
We can define it now.
Last week we ranked the twitchiest high school hitters in the 2027 class by Reactive Strength Index — how fast an athlete’s tendons snap stored energy back into the ground. This is its companion piece, and it measures something adjacent but uniquely distinct. RSI told us how quick-trigger the coil in …