Can 454,000 Norrathians be wrong?

From SirBruce's terrific MMOGCHART.COM, regarding the subscription levels of Massively Multiplayer Online Games:

"EverQuest (Accuracy Rating: A)
EQ’s figures pretty much speak for themselves. At one point their growth seemed nearly unstoppable, but the trend began to slow, and after peaking at about 460,000 subscribers, it now appears EQ is shrinking. Indeed, the latest press releases from SOE are quoting only “over 430,000” and in their announcement of EQ’s 5th anniversary the claim only “over 420,000”. The latest two data points on the graph come not from press releases, but from inside sources, and they show a somewhat different picture than what was indicated before – EQ reached some 550,000 subscribers in September 2004, and as of June 2005 stands at 454,000. It is important to note that the more recent data points represent not just total monthly subscribers, but also subscribers with active accounts on free time, eligible accounts on game time cards, etc. It is possible that the earlier figures from the SOE press releases were deliberately conservative, and/or did not count such accounts, thus accounting for the discrepancy. "