The irony is that the 2013 season so far has been much better than 2012 which was a let down in terms of on-the-field action. I've watched several of the Sky games so far and enjoyed them all.
I would say instead of just going for the reason of the Playoff format being the problem I would instead look at how well clubs are promoting their games. You see when it's done well (the Wigan Big Ones series) it has a good effect. Obviously this costs money in marketing it so it depends if the increases in crowd cover that extra cost.
Also I liked to see when the football season ends, Sky have a SL game on a Sunday at 2/3pm featuring some of the bigger match-ups. You're always going to hit a limit to how many you'll attract on Friday and Saturday nights to games as people will have many other options on those nights/times than their Sunday afternoons, it also helps more travelling fans attend.
Looking at the viewing figures on BARB, football regularly gets around the 1.5million mark for Sunday games on Sky Sports 1. Last summer in the football off-season only 1 or 2 events on Sunday afternoons managed to break 500,000 (England Cricket games) after them nothing registered anything really better than what SL does on a Friday night.
Surely their is a potential for big Sunday Sky games? I know that some clubs prefer Friday nights but if Sky come calling wanting big games for Sunday afternoons then they'll get what they want. Looking at last years fixtures played on a Sunday inbetween the period their was no football (10 Rounds) then probably the biggest game on paper scheduled was Hull vs Saints, a good game but definitely can go bigger than that.