Greatest tactician and overall greatest of all time is Eliud Kipchoge.
Evidence from races against Haile and Bekele and El Guerrouj shows this in the past.
He had one of the best finishing strides ever. I say had because he does not have to outstride anyone now.
He can start quickly or slower and he can choose his menu of tactic as he runs and switch it up as needed.
Eliud Kipchoge is to natural running tactics in a race as Michael Jordan was to natural tactics on the court.
Lagat is good, the late Richard Chelimo was good (RIP Richard...taken far too young), Sammy Wanjiru was a great marathon technician (RIP Sammy as well)
BUT
This greatest technician title has Kipchoge all over it