Optimal pacing for generating max power for short efforts (in this context say shorter than vo2 max duration) is to start harder and hang on. You get to fully recruit more energy systems than if you even pace or negative split by going out harder. For longer, aerobic efforts, the advantage of blowing out the more rapid energy systems is diminished, and the cost if you go out too fast is high, so targeting negative split only gives up a tiny bit of potential speed but averts a lot of risk.