Are these metrics truly indicative of an individual's skills? No. In fact, many applicants might print their application on hot pink A4 hoping to get noticed (and hoping that attention is positive).
Even with this tool, I'm merely reducing your applicant pool -- not selecting employees for you. My previous company used a few personality profile tests that were very effective in identifying people who'd work well at the company and with one another. That's not really the point, though. The point is determining who is a good Java developer and who isn't. Most recruiters I've dealt with know only buzz words and can't differentiate between well-qualified candidates and those who "used Oracle 10g to port BSD to J2EE over XSLT."
If your preference for UI engineers leans one way or another, the system would make appropriate corrections to the recommendations. Rather than getting a UI engineer who needs to work closely with a back-end developer and visual designer -- one who can pretty much only manage CSS and Flash work -- you can get results that include people who are more comfortable with the MVC framework, can handle templating in various languages, hates action script, can sling javascript in their sleep, and has a keen eye for visual design.
I'm not offering a one-stop, all-inclusive solution. I'm merely suggesting a method by which to intelligently and functionally reduce applicant pools to something the HR department can handle.