The Player Salary Floor is what you will pay regardless of your salary at minimum. Three quick examples to illustrate, with the floor being 100K for each of them to make it easy.
Team Salary - 62K
PSF - 100K
Pay each week - 100K
Team Salary - 100K
PSF - 100K
Pay each week - 100K
Team Salary - 150K
PSF - 100K
Pay each week - 150K
Basically, if you're under the PSF, there is absolutely no reason not to have more or higher salary players on your team.
(http://www.buzzerbeater.com/community/forum/read.aspx?thr...) For more reading.