For 6-max there are 6 explicit positions - BB, SB, button, cutoff, MP, EP.
For more than 6 players there are more than one EP or MP seat, but the first 4 remain explicit.
Our research shows that players' stats don't vary much between the positions which are grouped together at larger sized tables, so it shouldn't really be necessary to split them any further.
Should you wish to do so you will need to create custom stats and include a check for position using:
cash_hand_player_statistics.position = x
(or tourney_)
..where x is the position you're interested in. 0 is the button, 1 is the cutoff, 2 is the hijack, etc.
The old PT3
Tutorial: Custom Reports and Statistics explains how to make positional versions of a stat, and the mechanism is basically the same for PT4.