A picture is worth a thousand words. And when the funder has limited your proposal to 20 double spaced pages with a 12 point font, saving those thousand words is worth a diagram or two.
Putting a diagram together, especially when the clock was ticking closer to my deadline, gave me the hee-bee-gee-bees. Then I learned the easy way.
Forget about WORD -- go straight to PowerPoint. Design your diagram there. You'll find you have much more control. The tools are plentiful and easy to master. The end product will look much more professional.
Once you're happy with it, just copy and paste it into your WORD document. Great diagram, no grief.