When the SARS commissioner cleared his office, he left unhappy staff behind. In surveys, most were classified as "detractors" - people who would not recommend working at SARS.

The most unhappy were the group of executives and chief officers, the highest-ranking people at the revenue service. This was when former SARS boss Oupa Magashule resigned, not this week's exit on suspension by Tom Moyane.

It also turns out that SARS has not been adequately assessing South Africa's super-wealthy because its data is outdated.

It works on far fewer high-net-worth individuals than are tracked by New World Wealth, and there are only four dedicated auditors for a sector that should yield a higher take.

Instead, SARS uses tax amnesties to get really rich people to come clean on wealth exports without taxation.

And the customs processes at OR Tambo International Airport, Beit Bridge and Durban Harbour are so inefficient that the losses to the fiscus are apparent even to the untrained eye.

While SARS is now in crisis, big, intractable issues go back beyond the era of Tom Moyane, the commissioner so dramatically suspended by President Cyril Ramaphosa on Monday after he refused to resign.

As a new commissioner prepares to take the helm, it's worth looking at what studies have found at SARS.

Public Enterprises Minister Pravin Gordhan plays a much bigger role in Ramaphosa's government than that of a single-portfolio cabinet minister. His imprimatur is all over Moyane's axing. And because SARS is his baby (he is credited with the re-creation of the taxation authority, taking it from the lumbering apartheid Department of Inland Revenue to being one of democracy's best institutions), he may not brook criticism as he helps Finance Minister Nhlanhla Nene stabilise SARS.

We have tended to put SARS on a pedestal

But there is much to fix.

Another example of poor data at SARS is its assumption that there are 750000 small and medium-sized enterprises that are taxable. FinScope has found there are 5.98 million SMEs in South Africa. While many are informal or mom-and-pop micro-enterprises that are not tax viable, it still suggests there is an undercount at SARS.

It has also been found that the tax compliance burden on all businesses is 25 days but it impacts small and medium-sized businesses most.

All this is making South Africa's historic tax gap worse and means it is not closing quickly enough, placing the burden on too few South Africans.

Other issues a new commissioner should look at include the fact that SARS has race problems, with black staff feeling marginalised. This contributes to destabilising SARS as it leads to leaks and infighting. Moyane added fuel to the fire with an edict that all senior managers at SARS were to be black African.

Moyane is said to have decimated the Large Business Centre, the auditing hub for big companies.

With almost 85% of Large Business Centre debt disputed, if anything, the centre needs strengthening.

A third area that needs investigating is whether eFiling is as good as it is assumed to be. A recent study has shown that 45% of eFiling is done in branches by agents, which suggests the system is still too inefficient.

There are so few public institutions to be proud of in South Africa that we have tended to put SARS on a pedestal, but research shows that a new commissioner is going to have to take a long, hard look at this jewel in our public crown.

Moyane messed up big time, and he did not have the skill or temperament for the job - but the problems at SARS do not start and end with him.