How Geno uses freshman depends both on the freshman themselves and the team he has coming back. I think there is little question that the 1998-9 freshman class (TASSK) was the best freshman class ever, but they came into a pretty stacked team and except for a PG didn't really need starters, and then Sue went down.
The 2012-3 freshman were probably the next best group but came into a team with starters of 5th year Doty, senior Faris, juniors Dolson and Hartley, and sophomore KML.
The 2002-3 team had just lost 4 first round draft choice starters and needed a strong freshman presence to make up for the graduates - and Wolff was actually the most important one as the new PG until she went down and unfortunately was never the same player when she recovered.
With how important PG is, it is pretty interesting to note that Geno has turn the job over to a freshman so consistently - Sue in 1998-9, Wolff in 2002-3, Montgomery in 2005-6, Doty in 2008-9 (shared), Hartley in 2010-11. I don't think that is really from choice but more necessity. When Jefferson and Dangerfield arrived he had upperclass options and they had a season to mature.