I think there are a number of players that if they take a big step forward, could really help the team. Here are my suggestions: 

Braxton Miller - Braxton is great but if he can take the next step and complete more in the range of 70% of his passes I think it would make the offense basically impossible to stop, but he cannot act like he did against Buffalo where he is so hesitant to run that it ruins the play. His legs are an asset, he has to use them, but if he is deadly in the air then good luck dealing with Braxton, EZE, Dontre, Rod Smith/Dunn and the other receivers. 

Offensive Line - Pretty simple really, if this offensive line can play close to what we had last year, it will be tough to stop the offense. This is a high bar but this would be great. I also think that the talent on the offense should take some of the pressure off the line. 

Curtis Grant - I think we've been hoping for this for three years. Curtis Grant, given his physical size and speed should be the best linebacker on this team, unfortunately he hasn't put it together yet, I hope that changes. If it does, it will give us a great addition to the linebacking corps and really allow the defense to flourish. 

Eli Apple - Apple was a highly touted recruit but one that I could see being a huge part of this secondary. If he can step up and play I think he could really help the defense. 

Doran Grant- Replacing Bradley Roby is no small task but if he Doran can help fill the void left by Roby I think that we will see a big improvement in the pass defense. The addition of Chris Ash should really help all the cornerbacks in their development and play.