It is the "guts" of the evaluation that will tell you if you win or lose on it. 

I felt that my quantitative background can give me a great advantage because I probably spend more time on excel analysing and building models than most agents out there.

You'd need to work the numbers as a win for you and them. 

Something I did was build my own excel sheet from looking at several different investors who also give out advice.

I am becoming very frustrated with my investor as I continually send good flips her way with excel spreadsheets to back up repair estimates (we own a remodeling company so we are pretty good at figuring it out) as well as CMA's that back up my ARV because I am a licensed agent with access to the MLS. 

Excellent.

@John Pflederer hard to say without knowing exactly where your property is, but looking at your numbers I'd say you have a winning property but just don't know it yet.

Win win in my situation.

They can be an excellent partner!

Tax Deed Auction (winning bid) How did you finance this deal?