Message: Log cabin, "Whatever mileage is being done is being done too fast (for performance level)" simply means that even if the runner if doing 70-80-90mpw (which many people think is all you need to do for aerobic development), if there is no relationship between race performances, then that mileage is being done at too fast /too intense a pace to stimulate the greatest aerobic development. (In other words, if they slowed the pace down, they could get better). This will be explained more fully in later posts.
Pete, I have to be honest and say that I don't know too many runners who go for (short) runs at 25 secs/mile faster than M-pace. Since, according to Horwill, M-pace and 10k pace should only be 32 seconds apart, you are talking about boogieing along at v. close to 10k pace. That's quick. I'm confident you will achieve better results if you follow your (wiser) friend's advice to slow it down a tad. Enjoy the read of the other thread.
Part II should come on Sat. (There may always be a coupla days between the longer posts.)