how did you calculate this?
4 000 000 total frags in ~8 months.
On that note I calculated how many seconds there is in 8 months. With rough figures:
60*60*24*7*8 = 4838400
Total kills = 4 000 000
4 000 000 / 4838400 = 0.8267195767
On that note, adding into account not using exact perfect figures of how many days where in those exact 8 months it's approximately 1 frag per 2 seconds. However you could argue it's 1 frag per second.