Update: The Archaeologist was fine.
Proof of problems with Stats: Soldier Stats page & Engineer Stats page
With the sky trooper we see he has 7 player vanquishes and 5 KO's, which means a ratio of at least 1.4, assuming every KO was by a player. However the stat we see is around 0.30 which is the around the same as 7 divided by 23, which is the number of KO's the Artic trooper has.
Similiarly for the landscaper, he has 23 vanquishes and 22 KO's which should leave his a k/d ratio of 1.04 or 1.05 depending on whether the stats page rounds up or not. However we see a ratio of 11.5! Right next to it we see that the plumber only has 2 KO's, which is convenient, as we can see that 23 divided by 2 = 11.5, the exact number.
Also if you add the vanquishes for the all the footsoldier variants including the Base footsoldier, it should total 499 vanquishes, but the Overall vanquish count is 514, which is clearly higher by a significant amount. Similarly for the engineer, the total vanquish count should be 652, but instead we see 661 vanquishes.
Now as I mentioned before it may tally up the total vanquishes slightly differently, such as counting vanquishes by summoned zombies or potted plants, however the k/d ratio is clearly wrong, at least for my stickerbook on the PC version.