Bort doesn't have a stat penalizing Punters for touchbacks, nor does Bort reward punters for kicking the ball out of bounds instead of sending it deep.
There ought to be a stat for punters called 'out of bounds avg.' (average yard mark the ball goes out, if a touchback is kicked it counts as out at the 20) or 'coffin corner from' (similar to the range that kickers are making field goals from).
This will more accurately allow you to consider the abilities of the punter. Also, you are only rewarding distance (and perhaps tackling), when the punter should be rewarded for the following:
Distance
Tackles
Hang time of the Punt
Coffin Corners (rewarded)
Average Coffin Corner spot (rewarded the closer it is to 0, punished for being closer to 20 (touchbacks)
Touchbacks (punished)
The fact that the Punters are only being measured on the first two catagories is not reflective at all of a quality punter.