Eh, do quote fairly though:

"Although GPA has been widely analyzed, the research has produced inconsistent results. Some meta-analyses suggest that grades have relatively low validity as a predictor of job success (Bretz, 1989; Hunter and Hunter, 1984). Individual studies by Ferris (1982) and Schick and Kunnecke (1982) support the meta-analysis findings; these studies found no relationship between grades and performance evaluations."

In other words the state of research on this question, back in the early 90s when this article was written, was "inconsistent".