A lot of sponsorship deals are based around perception......and when you look at Superleague through the eyes of a non RL fan, you see a competition that is predominantly based along the M62, with a team in London that is badly supported (Blue Square premier type attendances) and a team in the south of France that has about 9k fans.
In total, about 90,000 fans attend matches every week of the season and SKY TV get between 90k and 190k viewers for it's 2 games a week. The competition gets very little in the way of mainstream media coverage.
Superleague did itself no favours by bartering a deal last year....it's always hard to charge for something you've previously given away with no conditions.....
Let's look at other sports and compare...
Aviva sponsor the other lot to the tune of 5 million a year. The get similar crowds to SL, but they get wall to wall coverage in the media and are associated with the juggernaut that is the England international Team which sells out 80k stadiums and wins tournaments on FTA TV.
Barclays sponsor the wendyball for 40 million a year....it is the #1 game in town, no matter what anglers say
Heineken claim have invested over 100 million in Rugby since 1995.....the European trophy and RWC rights give them massive reach across the globe.
Npower pay 7 million a year to get their name on the Championship....not as big as the premiership, but they have more fans on the ground every week.....decent media coverage too.
Aviva paid 10 million a year for Athletics....Olympics aside, that's a fair chunk of change for sports that only get sporadic coverage in the press.
Rory Mcllroy gets about 15 million a year from Nike

speechless!
Arsenal>Emirates 30 million a year....stadium and shirts.....good coverage in the media and a global reach.
Saracens>Allianz 1.5 million a year.....strange one this as sarries only get about 7k to games normally.....but someone somewhere sees a benefit to it.
England Union get 5 million a year from O2 for their shirts.....not bad for a team that played 9 games in 2012
Engage were rumoured to be paying 1.2 million a year........Stobart got it for nothing.....they'll do well to get 7 figures for it IMO.