Coen said earlier in the year that Leary leads, but he does so by example. Robinson has the most "seniority" of our star players since he's been here two years, so he would be the prime candidate on offense.
I have to think it would be weird for first year players in a new system to call any shots or jump down some younger dude's throats, so that leaves Leary and maybe Davis out. I agree Ray Davis has proven he can back up that talk, so I think it's possible he'll develop into a leader as the season wears on. The Vanderbilt game would be a great breakout opportunity.
On defense, I think we have to consider Wallace and D-Jack the leaders. Weaver could be that guy, but needs to improve his play if he wants to be a more effective leader – no more lapses or missed sacks/TFLs.
Iron sharpens iron, so I think SEC play will hone our leaders and we'll start to see who emerges – especially when our backs are against the ropes.