According to The Guardian on Friday, the Sri Lankan Twenty 20 template is 'an explosive opening partnership, nurdlers in the middle order and mystery spin to bamboozle the opposition.' This formula may have served the Sri Lankans well up to now, but wouldn't they be even more successful if they had an explosive middle order as well?
Of course, it's one of the major complaints with the 50-over format - those middle twenty overs in which the batsmen are happy to run every ball to long-on for a single, and the fielding captain is happy to let them. Twenty 20 was meant to do away with that, but, as Sri Lanka have demonstrated, it hasn't.
The fact is that it doesn't matter how many overs you play in a limited overs match, there will always be boring (or, at least, less exciting) middle overs. A team playing a one-over-a-side match would probably still have room for a nurdler for the third and fourth deliveries.
So it's not Sri Lanka that are to blame, it's the limited over format. Together with artificial fielding restrictions, those tedious middle overs are a symbol of the difficulty the shorter format will always have when challenging Test cricket as the primary version of the sport.