It all depends upon what criteria they are basing it on. Second largest in terms of passengers flown, daily flights, aircraft, capacity, etc. If it is based upon daily flights they might be right.
As of 1/1/2004 Oneworld had 7,909 daily departures (including Swiss):
http://www.oneworld.com/pressroom/se...s/F000cd01.doc
Without KLM, Skyteam had 7,865 in the summer of 2003:
http://www.skyteam.com/EN/aboutSkyte...fact_sheet.pdf
With KLM it is possible under this standard that they are larger.