Speed = top speed or distance covered over time
Power = weight x acceleration
Explosive = Rate of change of Power (in engineering terms it is called jerk)
(maybe a better term is effective application of power)
To PG's point it all equals to (in baseball)
40 time
60 time
(actually I prefer 15's for this)
Bat speed
Exit velocity
Steal times
Ball Velo
POP times
However there are a few very gifted athletes like Mike Trout who are truly Explosive IMO.
Now I will say that any athlete can make a significant improvement in this aspect of their capabilities, but few really put in the extra work to achieve it. My son has been working out with some guys from gymjones, and while they push their athletes physically, the real limitations are actually mental.