Lag and high pings can come from a multitude of things.
Internet routes are usually one of the most common problems users face. If a core router, or any device along a network path fails, the carriers will usually reroute traffic. This also happens when maintenance is done on the network. It's not uncommon to see routes going across different parts of the country instead of going straight to the destination because of this reason.
For example, if you live on the east coast and play on an east coast server, you should be routed directly to the server. If traffic is being rerouted you may get routed to California and then back to the east coast to bypass the problem.
Another issue, which has been said already, could be resource conflicts. Mostly problems with a server that it's experiencing high CPU or memory usage, thus creating lag. Network usage is also a factor as a DDOS attack on a server can bring the network to it's knees, make the server inaccessible, and cause connection problems (again, lag).
Hardware failures can also cause problems - failing hard drives in a RAID array can cause a decrease in performance in certain circumstances. Bad memory can cause memory errors which can propogate into crashes. Overheating CPU's can get throttled to keep them from being overloaded (degrading system performance) or even shut down the server completely.
So, who knows what it really could be. Let the leadership figure it out and solve the problem
