Power is "everything" - you don't jump without your arms, ya know?
Too many people divide this stuff up using "bodybuilder" mentality - upper body, lower body, etc. It is ONE body. We do medicine ball throws here, a lot of them. Our chest passes are very violent and our feet always leave the ground and move about a foot or so in distance. Our overhead work (forward/backward) are done with total body. Our box jumps are done with arms, as are the long jumps - watch anyone do a broad jump and watch their arms.
Training is so damn divided these days - it's all part of one program, one body. That is why we program all the important shit and am striving to make everyone BETTER. Hell, I just wrote the 5/3/1 recovery protocol that is in line with the entire program and easy to program/follow and evaluate. Another essential part of training that is left out.
I blame Weider.