A natural gas engine is much more particular about air fuel ratio than a deisel. The gas engine has fuel in it and then it fires with a spark plug, so it is easy to get into preignition, which is a silent killer. The pressure sensors allowed them to see the firing pressure trace and adjust ignition and fuel to stay out of preignition and detonation.
A diesel engine burns the fuel as it is injected, so it less likely to have preignition or detonation, but not impossible.
Another interesting fact, these engines are probably turning about 300 RPM, as opposed to our tractors turning 2 to 3 thousand, just think of the huge torque these monsters have.