Originally Posted by Nerd

Wrong. Patches or even fully new binaries could use TCP for sending the game data. This would eliminate packet loss completely, but it would add overhead and increase the likelihood of latency-related issues (like carrot kills etc.). Note that packet loss is the main reason for many lag effects, for example airhits (latency issues can commonly cause these too, though), 3HKs, fake carrots, non-spawning PUs and carrots etc.

Ping also tells much about lag, though, as the number of hops correlates with both the number of UDP packets dropped and the ping. It also causes delay in the movement of enemies, which might cause godmodes.