You should consult with your tax professional on the matter. 

Professional trade journals such as Accountancy, Tax advisor and others. 

A recent article in the Remodeling Magazine (a publication for professional contractors) made the case that if you don't mark up your subs by 40% you might loose money as a GC.

I played professional baseball for 4 years and don't have any experience in the real estate world.

Not true, but don't believe me or anyone else, go find the answer from qualified tax professionals!

Readers should seek professional advice.

I can generate some anecdotal examples, but would really like to see a professional study, existing court case, etc.

Unfortunately, on BiggerPockets, you sometimes have to be cautious, as some professionals listed there aren’t always reliable since realtors, lenders, and contractors pay for leads through BP with little background.

Interestingly, we have no record of you as a member Nate Our decade-long history of empowering real estate professionals speaks for itself, with countless testimonials from those who've genuinely benefited from our programs.It’s quite something to see someone with 1,055 blog posts engage in spreading falsehoods, seemingly to pick up leads and sales rather than running a legitimate business. 

Hi Jayvionne, Welcome to the community - There are a lot of good professionals and resources here on bigger pockets to learn and grow.