On Monday, PokerScoutreported that, over the previous week, online poker traffic had dropped for the fourth straight week. Of the ten busiest sites in the industry, seven saw their player numbers fall, with only PartyPoker and two others showing an increase. PokerScout opines that the reason for a 5% increase in the numbers at PartyPoker are due to a promotion tied in with the Euro 2012 championship football tournament, where players “collect” European soccer stars by earning frequent player points.

The biggest news on the online poker industry front is last week’s departure by Lock Poker from the Merge Gaming Networkto the newly formed Revolution Gaming Network. Completed last Thursday, Lock Poker left Merge by purchasing the former Cake Poker Network and joined that collection of rooms. The resulting move has rocketed the new Revolution Gaming Network up the PokerScout traffic rankings and dropped Merge down.

With only a few days of data, the Merge Gaming Network looks to have lost about 25% of its clientele following the Lock Poker defection, according to PokerScout. As of Wednesday, the Merge Gaming Network is showing only 858 cash game players on average, with a peak of 2,181 over the past 24 hours.

Meanwhile, the newly branded Revolution Gaming Network doubled its size with the addition of Lock, jumping up to 1,358 cash game players on average and a peak of 1,766.

Whereas Merge held a 3:1 advantage over the old Cake Poker Network prior to the changeover, that edge has now disappeared and the two are virtually equal in their ring game player numbers on PokerScout’s statistical rankings.

Although Merge lost a good deal of its action, the new Revolution Network has captured more than just the numbers lost by Lock’s former home. PokerScout surmises that this is due to the excitement surrounding the change from old Lock players and existing players on the re-branded Revolution Gaming Network.

In 2010, several sites including Sportsbook.com and PlayersOnlydecided to defect from the Cake Poker Network to the then-fledgling Merge Gaming Network. As a result of the move, Merge tripled in size according to PokerScout, which pushed the network to the busiest that still accepts American action. PokerScout believes that this switchback in Lock leaving Merge for what was formerly Cake may have a similar effect.

There are still some obstacles that might keep both networks from reaching their full potential, however. Merge and Revolution have taken the controversial step of still allowing American players to participate in their offerings, flying in the face of potential action by the United States Department of Justice. As such, PocketFives does not suggest that American online players sign up for U.S.-facing rake-based sites like you’ll find on Merge and Revolution, as your deposits could be at risk. American poker players are instead recommended to sign up for sites like HogWild Pokerand FaceUp Gaming.

The overall leaderboard for the online poker industry is still dominated by PokerStars, which has been #1 since October 2006, shortly after PartyPoker pulled out of the United States with the passage of the Unlawful Internet Gambling Enforcement Act.

The iPoker Network has barely hung onto second place in the industry, with PartyPoker creeping up behind it. Three nation-based sites – PokerStars.it, Winamax.fr, and PokerStars.fr – continue to be popular with players in Italy and France and are sixth, seventh, and ninth in the top ten, respectively. Merge still is the biggest U.S.-facing site and sits in eighth place overall.