A single plane going tech during peak season is hardly evidence that Qantas is a basket case. Yes, that has consequences for passengers. But, that is part of the reality of travel - things don't always go to plan. VA had a complete meltdown in SYD over the weekend; Bestjet went into administration just before Christmas; Frontier had an A320 take off with an unsealed door on Christmas morning, which led to passengers not arriving until nearly 4am on Boxing Day.
Taking an airline-wide perspective, Qantas has just been named as the sixth most punctual airline in the world. Even if we take OAG's findings with a grain of salt (and they quite properly note all the usual caveats), its OTP is still very strong.