I always understood Alexa's number was based solely on results gathered from those using the Alexa toolbar.

Even worse.

Your new folks need to get over this and concentrate on proper metrics - like traffic derived from search engines (broken out by engine) and any conversions from that traffic.

Follow the money.

As for actually using G-PR and Alexa data - it can be useful stuff if viewed as a trend - over the longterm.

Trouble with G-PR is the data you see in the graph is out of date - by about 4 months or so - so how you're rating the site and how G is rating the site could be miles apart...