PizzaWell valve doesn't exactly make sure that everyone is ok with the time at which they roll out updates, do they? Patches pretty much come out on a feel-like-it basis. Hard to predict server traffic based on this.
You're right that prediction is impossible, but even notification if there is ongoing trouble would be really helpful. ESEA has for instance a twitter that they could use to give notice if there is currently major technical work on specific servers. Right now it seems they're just posting links to CS frag vids. Actually a lot of the linked videos are to demonstrations of changes in updates in CS:GO which is a rather nice idea.
Ideally there could be another column in the ESEA client for each server giving the cpu load or whatever in the past 5 or 10 minutes as something like a green/yellow/red icon and a "state of the system" in the MOTD but I doubt they would ever go that far, especially given how much manual work by admins is required for switching servers on the fly. Maybe easier just to keep everyone in the dark.