Of course Duke is much better with Ryan Kelly on the court. He may be their most invaluable player, as Duke has nobody else on the roster that can stretch the floor, while playing great help defense.
That being said, Duke has one key weakness, Depth. If you watch a lot of Duke basketball you know that Coach K's teams have one consistent weakness: lack of depth.
This is not to say that Duke doesn't have talented bench players, but rather, Coach K prefers to play a relatively short rotation. Who am I to question the most winning coach in the history of D-I ball, sure. But throughout the years I've noticed his short rotations have held Duke back a bit.
Usually this lack of depth doesn't prove overly problematic until tournament time. After playing extended minutes throughout the season, Coach K's stars often seem to slow down or burn out at the wrong time (see: Singler, Kyle and his shooting slump during his senior year).
Besides wearing his starters down, the short rotation makes Duke vulnerable to foul trouble. Imagine a scenario where Duke plays Indiana in the tournament, and Mason Plumlee gets into early foul trouble. There's no way Duke could win that game without an inside presence.
In recent years, a lot of talented (and some overhyped) recruits have transferred from Duke due to a lack of playing time early in their career (see: Eric Boateng, Jamal Boykin, Olek Czyz, and most recently Mike Gbinijie). I understand Coach K's slow growth model (in the vein of Shane Battier) but the AAU circuit has changed the recruiting game. Player's want instant satisfaction, and coaches like callipari have thrived by adjusting to that.
Anyway, this brings me to my main point. Ryan Kelly's injury will force Coach K to extend his rotation (unless he decides to give those minutes to Josh Hairston, who most recently put up a 1 point, 1 rebound masterpiece in 16 minutes versus clemson). I know that Coach K is hesitant to trust his young players, but I hope this injury scares him a bit. There's no reason to play your starters from 25-35 minutes against Florida Gulf Coast, that is time to develop confidence in young players.
Ryan Kelly is supposed to be out from 2-4 weeks with this injury, which will provide ample opportunity for youngsters Alex Murphy and Amile Jefferson to step up.
Murphy was billed as Kyle Singler clone out of high school. He's tall for the 3 and skinny for the 4, but he brings a bit of skill on the offensive end, with some 3 point shooting, and some ability off the bounce. He seems to be a pretty good perimeter defender as well, but remains in Coach K's doghouse for some reason.
Jefferson is much more interesting. He showed great skill with his back to the basket, as well as facing up from the high post when in high school. In limited minutes he is rebounding at a higher rate on offense, and similarly on defense, than ryan kelly. He has played well thus far, and It will be interesting to see how he does with an increased role.
Marshall Plumlee could get some run here too, but he's coming of a couple injuries, so he may be limited for the time being.
This is an interesting predicament that Duke is in. It will be interesting to see the adjustments they make, and if it will force coach K to expand his rotation. Duke's game vs nc state should be a good indicator of what coach K will do.