For those who use any form of GUESS ratings/GD Reports, own modified formulas, or spreadsheets -- do you "baseline" the attributes before applying the weight? For example, from the "old" player's guide it listed Solid Core Values and Star Core Values. Do you subtract these before multiplying the various preferred weights? Does it significantly change the results than just multiplying without baselining the values?

I sort based on cores, but I don't modify the formulas. I've tried it in the past, and it wasn't pretty.

Before I started using the GUESS reports and equations, I tried to do what you are talking about....but just using NON-weighted cores.  It was better than nothing, but not as good as weighted cores.

Since then, I have made some modifications to some GUESS formulas, but have not attempted to do this "baseline" thing.    I have established "minimums" that I look for in recruits and that separates the men from the boys, then I just try to get the best guy that meets my minimums.

In years past I recruited based on the formations I used in that particular world. IE, if my primary offense was ND or WB then I revised my TE weights to favor blocking and strength and I made sure to recruit at least one RB with solid blocking skills.  If I ran trips I revised my RB weights to favor blocking and strength.  If my def was a 5-2 I revised my LB weights to favor speed.  There are a few other examples but this worked well...just required a bit more work.

I don't subtract baselines, but that could be a great idea. I use formulas similar to GUESS in a spreadsheet I built --- used same one for years, with tweaks to the formulas.

I could probably eyeball, but I like using a spreadsheet.