1st off, Mayo will be fighting Beasley for the ball all the time. He wants to be a scorer 1st, preferably the 1st option. His percentages don't warrant that, but neither do Beasley's.
2nd the reason I mentioned Warrick and Childress is that's what type of contract it will take to sign Mayo. 4 yrs. min. 30 Mil.
You can overpay Shannon Brown for a year and then be done. With Mayo your stuck again. For what? A number 13 lottery pick again, maybe 10. Then you have him another three years on a continuing retooling project, that just took longer.
Mayo could avg. your 18-20, but he won't help you win much down the road. Just enough to suck not bad enough. The Suns have to take their medicine and hope for better days and continued CAP flexability next season.