ORIGINAL: Mad Russian
That chart seems suspect to me because it shows the 75mm being more efficient than the 88mm at killing Soviet tanks at some ranges. Considering a myriad of reasons, not the least of which are the 88's greater penetration value and Soviet tanks greater armor factors later in the war, I find that hard to believe.
Good Hunting.
MR
It could be a problem with the source of course, but I am pretty sure that it's just statistics. The curves are normalized in such a way that the total area below each curve amounts to 100% *for each calibre*. It does NOT say anything about the *relative* number of kills. So the two distributions really just say that 'kills from 75mm happened with greater frequency at ~ 500m, while kills from 88mm guns happened at ~ 1000m. If the 37mm AT guns was shown as well, it'd show a 100% peak (I am guessing) at 200m. That does not say that it was better than the 88m! Just that it'd only kill at short ranges. The distributions actually *do* support the common knowledge that 88m were better, it shows that they were able to kill from further away, without having to wait for the tanks to close in.
Also, the plot does not show the distance at which a gun would be *most efficient*, that 'd be likely a decreasing histogram, with short ranges preferred. But it says that averaging over many engagements most kills happened at distances larger than 500m, mostly because neither tanks nor AT guns liked to be very close to each other (or the enemy supporting infantry).