Lets not get into a blame game here. Tiger has played a role in many of the delays as well.
Suffice to say, 80% aint too bad for a new start. Let's look at other airlines just as a comparison.
On time performance – total industry for February 2008
(from the DOTARS website)
Jetstar 73.0
M@CAIR 71.4
Qantas 82.8
QantasLink 76.6
Regional Express 82.0
Skywest 77.2
Virgin Blue 79.2