You don't have a pool of 12 million players to pull from for your random queue at any given second. A large percentage of those players don't even play in the same region as you, so let's overestimate a little and say you are only in the same region as half of the playerbase. So right off the bat, that's 6 million players you cannot have access to if you play on North American servers. From there it's broken down further into battlegroups. Battlegroups are based on server clusters in different physical locations throughout the United States. They're split up across Boston, Dallas, Los Angeles and Seattle. Players in different areas of North America can choose a datacenter closest to their area to reduce latency.
There are a total of 13 battlegroups. Those 6 million players are not split evenly across all battlegroups, but let's pretend they are. Rounding up, that would put roughly 500,000 players per battlegroup. You only really have access to less than 500,000 of WoW's 12 million players, and the real number is probably a lot less depending on your battlegroup. Of those potential 500,000 players, only a fraction of them are even queueing for randoms at any given time. A lot of them are leveling alts (or leveling for the first time), raiding, doing dailies, just being social or doing some other thing. And they're not all logged in at the same time. That's 500,000 players total, not 500,000 every second of every day. Edit: And has been pointed out in the comments numerous times, about half of that 500,000 is on the opposite faction and you can't group with them at all. That brings it down to 250,000 if you assume a perfect Horde/Alliance split.
That's not the end of it, either. Of that small fraction of players, how many of them are tanks, healers and DPS? They can't just throw any five people together. You need a 5-man group with a tank, a healer and three DPS. The number of available players are limited even more when taking group composition into consideration.
That's why groups are not instant.
"How high will the Strength of Wrynn go? How often is it increased?"
So far the buff has gone up 5% every 3-4 weeks and it will go as high as 30%. We'll be hitting that in 6-8 weeks, and by then we should have the Ruby Sanctum to keep us busy, though I can't say that with complete certainty. Considering testing is supposedly going well, I can't see Ruby Sanctum being more than two months away.
"Why haven't they patched the under Stormwind glitch already?"
Is it gamebreaking enough that they really need to worry about it before Cataclysm revamps all of the terrain in Stormwind? I'm not saying that's Blizzard's reasoning, but on the list of things that absolutely must be fixed immediately in the interest of game balance and stability, being able to get underneath Stormwind is probably pretty low.
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