3-bet and 4-bet stats are done as a % of opportunities. I could have a pfr of 1% vpip of 10% but a 4-bet of 100% since when i get 3-bet my range is ultra strong and I 4-bet 100% of it.
Also 120 hands 4-bet won't have even come close to converging to the true value, same for 3-bet.