Quincunx and Keppie\'s hypothesis

[Cesco]

To Brayan: "However Scipio caused the wounded to be carried to the rear, and the hastati to be recalled from the pursuit by the sound of a bugle, and drew them up where they were in advance of the ground on which the fighting had taken place, opposite the enemy's centre. He then ordered the principes and triarii to take close order, and, threading their way through the corpses, to deploy into line with the hastati on either flank. When they had surmounted the obstacles and got into line with the hastati, the two lines charged each other with the greatest fire and fury.Being nearly equal in numbers, spirit, courage, and arms, the battle was for a long time undecided, the men in their obstinate valour falling dead without giving way a step"... Indeed from this quote i can only suppose the gaps were closed by the principi and triari " taking close order". The battle was very long and i don't believe that a simple acies could resist a long time with gaps. But this is only a speculation.
The more i think to keppie's hypothesis the more I'm doubious about it:I have find no evidence to prove a tactical role of centuriae,while the tactical unit was ( only ? ) the maniple. Maybe the centuria didn' t even exist on the battlefield... so IF the gaps were closed it was the maniple to manouvre ( maybe lining up the men as described by Vegetius I.26 in order to doubling the front or the number of ranks...)
Anyway thanks for the advice! I'll try to find the paper. by the same autor i'd like to report "Roman Soldiers in Open Order: Polybius 18.30 and the Visual Evidence" and regarding intra-manipoular manouvres mentioned above:"http://www.academia.edu/727113/_Not_so_different_individual_fighting_techniques_and_small_unit_tactics_of_Roman_and_Iberian_armies_ by Fernando Quesada Sanz