Here's a list of the 38 current Buckeye players who were recruited to play defense, and how I would rate them as of today (star, hit, miss, bust, unknown):
Class of 2009
C.J. Barnett............hit
Pittsburgh Brown........miss
Class of 2010
DL Darryl Baldwin.......bust (moved to OL)
DB Christian Bryant.....hit
DL J.T. Moore...........bust (moved to TE)
CB Bradley Roby.........star
Class of 2011
DL Michael Bennett......hit
DL Chase Farris.........miss
LB Curtis Grant.........miss
CB Doran Grant..........hit
DT Joel Hale............hit
DE Steve Miller.........miss
LB Ryan Shazier.........star
DB Ron Tanner...........miss
Class of 2012
DB Devan Bogard.........unknown
DE Jamal Marcus.........hit
LB Joshua Perry.........miss
DB Tyvis Powell.........unknown
CB Armani Reeves........miss
DT Tommy Schutt.........hit
DE Noah Spence..........star
DL Adolphus Washington..hit
LB Camren Williams......miss
Class of 2013
DB Eli Apple............unknown
DB Vonn Bell............unknown
DL Joey Bosa............star
DB Cam Burrows..........unknown
DB Gareon Conley........unknown
DT Michael Hill.........unknown
LB Trey Johnson.........unknown
DB Darron Lee...........unknown
DE Tyquan Lewis.........unknown
LB Mike Mitchell........unknown
DT Donovan Munger.......unknown
DT Billy Price..........unknown
DE Tracy Sprinkle.......unknown
DB Jayme Thompson.......unknown
LB Chris Worley.........unknown
Stars.......4
Hits........8
Misses......8
Busts.......2
Unknowns...16
So there are a lot of young, inexperienced players on defense who have not yet had a significant chance to play, and many of the older players have not reached their potential. Note that there are only two fourth-year and two fifth-year players on defense.
Of the "star" players, Bradley Roby has severely underperformed this season after an All American campaign in 2012. I have Joey Bosa ranked in this category, but clearly his best days are still ahead of him. Ryan Shazier and Noah Spence have both performed very well, but neither has provided enough impact plays this season.
Of the "hits", C.J. Barnett makes the list primarily because he is a multi-year starter; his erratic play could easily land him in the "miss" column. Christian Bryant's career is over due to a season-ending injury. Of the remaining payers (Michael Bennett, Doran Grant, Joel Hale, Jamal Marcus, Tommy Schutt, and Adolphus Washington), none has shown "star" potential to this point, although Marcus, Schutt, and Washington still have plenty of time to develop. Note that former offensive lineman Chris Carter would rate a surprising "hit".
Of the "misses", Curtis Grant is the most disappointing, not only because of his immense potential coming out of high school, but also because a solid middle linebacker could really shore up this defense. Joshua Perry has also been a disappointment, and he will need to improve greatly in order to remain in the rotation next season. Steve Miller has provided some valuable minutes at defensive end, but there is almost no chance that he will ever be able to supplant younger, better players like Spence, Washington, Marcus, and Bosa.
The "bust" category is misleading, since the vast majority of the busts are no longer with the team. The following 20 players would still have eligibility, but left the team due to injury, discipline, or transfer:
Class of 2009
LB Dorian Bell
CB Dominic Clarke
DL Melvin Fellows
LB Jonathan Newsome
LB Jordan Whiting
DB Jamie Wood
Class of 2010
LB David Durham
DB Adam Griffin
DB Chad Hagan
LB Scott McVey
DE Jamel Turner
Class of 2011
DB Jeremy Cash
LB Connor Crowell
DB DerJuan Gambrell
DE Kenny Hayes
LB Ejuan Price
Class of 2012
DB Najee Murray
LB David Perkins
DL Se'Von Pittman
LB Luke Roberts
Although few of the "busts" listed above would have seen significant minutes anyway, Dominic Clarke proved in his brief tenure that he could provide valuable depth at cornerback, and Melvin Fellows, Scott McVey, and Jamel Turner were all very highly rated prospects who never saw the field due to injuries. Safety Jeremy Cash transferred to Duke in the midst of the TatGate scandal, and he now leads the Blue Devils with 66 tackles, to go along with 7.5 TFL's, 2 interceptions, and 2 forced fumbles.
So, bottom line, I'm voting for "talent" - too few stars, too many busts, not enough time for the young talent to emerge.