- Edited
The scoreboard shows the ping as the server sees it, while stat net shows clientsidely calculated ping.
...and I think it can be presented more or less like this:
F1 ping = ping + (1000 / fps + 0.5 * 1000 / tickrate) * 0.5
F6 ping = ping + 1000 / tickrate + 0.5 *1000 / fps