GangPlank and farm count

I've noticed numerous times in games that my farm fluctuates. For instance, I was at 426 farm and it went down to 37x and then it went back up to like 400. I have had it happen numerous times. Wondering if anyone else has had this happen, does it have something to do with farming with the barrels? I have also had it where I had like 370 farm in game and in the lobby after the game it shows around 320.