If the facilities were in any fit condition to be used, the local Athletics Club might prefer to use them, rather than have to hold competitive "home" fixtures in Derby, in some cases. It's chicken and egg. Neglect the by-pass, say, for long enough and no-one will use it, but that doesn't mean that it wouldn't be used, if it was fit for purpose.
At some point in the past, the local athletes must have given up hope of QPA ever being brought up to scratch, and moved elsewhere. I wonder if they had meetings with the council about it, before doing that?