There's no good way to do this. Even if you base it on a metric such as bench, it's incredibly hard to find that info outside of top recruits/players. You can't really base it on weight either, otherwise lineman will have to have 99 Throw Power. I think it's best to leave it unregulated.
For certain stats like speed that are more easily measured and much easier to find info for, I'm okay will possibly structuring it more in the future. I don't think every single stat requires a scale though.
We've been talking about this and it seems like a good possibility in the future. We need to get the Inactive editors that are planning on returning for the 2016-2017 file in on the discussion before making any decisions.