I actually do think it's a coincidence that the stock price is down 38% since purchasing OMGPOP. It had a nice run up based on positive news related to the Facebook IPO, so when the market began to contract in late March/April, people took their profits. There hasn't been much positive news since then, so it hasn't rebounded. In fact, the whole technology sector is down about 32% since late March (it was +20% on the year, now its only +13.9%)[1]. Basically, I don't think the OMGPOP acquisition has had much of an effect on the stock price.

[1] http://www.google.com/finance?catid=66529330