If all political careers end in failure, then Angela Merkel is the exception to the rule. When Germany goes to the elections on Sunday, the chancellor will not seek re-election after 16 years in power.

Merkel has achieved what few other political leaders manage: to retire of her own volition.

But just because Merkel’s career did not end in failure does not make it a success. Her country desperately needs reform, her party is in shambles, and the political system fractured and polarised.

It would be unfair to blame her alone for these problems. However, Merkel has been the dominant force in German – and perhaps European – politics of the past two decades.

Given Merkel’s background, that supremacy is astounding. The story of Merkel’s entry into politics remains telling, even 30 years later.

At the fall of the Wall in 1989, Merkel was a 35-year-old physicist at the East Berlin Academy of Sciences. She was not a revolutionary and only entered politics after the fall of the East German regime.

Merkel apparently contemplated joining the Social Democrats at first but was put off by some of its members at a meeting. The Christian Democrats did not appeal to her, either. Instead, she joined the political splinter group, Democratic Awakening.

Just a few months later, Democratic Awakening merged with the Christian Democrats. Merkel was now a member of a party she had not chosen. Regardless, it boosted her career.

Chancellor Helmut Kohl needed some diversity in his post-unification government. Merkel’s role as a female East German Protestant helped balance Kohl’s male-dominated West German Catholic cabinet.

Most other political careers at least start with a set of convictions. Merkel, meanwhile, almost accidentally found herself as a Christian Democrat at the cabinet table.

Unlike other senior politicians, Merkel could not draw on decades-old networks. All she had was Helmut Kohl’s protection, who called her “my girl”. She used her position to observe the physics of power up-close.

When Kohl lost the 1998 election and later got embroiled in a party donations scandal, Merkel showed how much she had learnt from him. She distanced herself from both him and party chair Wolfgang Schäuble.

It was a brutal coup in which the leadership of the Christian Democrats fell to Merkel – only 10 years after entering politics. Merkel’s political positions and beliefs, however, remained a mystery.

The lurch to the left of her Christian Democrats also opened a political vacuum on the right.

In the 2005 election campaign, Merkel sensed Germans wanted even more economic reform than Chancellor Gerhard Schröder had started. She enjoyed comparisons with the young Margaret Thatcher and even toyed with a flat tax. No reform was too radical to be considered by Merkel.

Still, the election result was a near-disaster for Merkel and her Christian Democrats. Instead of securing an outright majority, she narrowly defeated the Social Democrats, with whom she formed a coalition.

It was the last time Merkel talked about economic reforms. That political experiment had failed, and she would not repeat it.

From a Thatcher clone, Merkel morphed into a politician whose primary goal was not to scare anyone. Her chancellery commissioned record numbers of opinion polls on every aspect of policy. At one point, Der Spiegel termed Merkel’s approach “government by numbers”.

Merkel also tried to rob her largest political rivals, the Social Democrats, of political oxygen. Long-standing Social Democratic policies such as the minimum wage suddenly became Merkel’s.

It was all part of Merkel’s asymmetric demobilisation strategy: leaving other parties’ supporters with nothing to campaign on while guaranteeing her own supporters turn out in sufficient numbers. It was as cynical as it was effective.

Merkel’s political positions were fluid as she adapted them to her needs. For the military draft, and then against it. For nuclear power, and then against it after Fukushima. Against a bailout for Greece, then for it. Against multiculturalism, and then opening the borders to millions of Arab migrants in the refugee crisis. Against same-sex marriage, then for it. The list of Merkel’s flip-flops is endless.

While these tactics have kept Merkel in power for the past 16 years, the overall impact on German politics has been disastrous.

Her own party is a shadow of its former self. The Christian Democrats have little programmatic identity left – and even fewer capable politicians.

The lurch to the left of her Christian Democrats also opened a political vacuum on the right. The Alternative for Germany, a group including far-right radicals, filled it.

Finally, none of Merkel’s promised economic improvements materialised. No tax simplification, no modern infrastructure provision, no scaling back of the byzantine bureaucracy.

Former defence minister Peter Struck once said Angela Merkel would make a perfect pilot. With her in the cockpit, everyone feels safe and relaxed. “Only you never know where you’ll land with her.”

Merkel has governed Germany for 16 years, but she never led it.

Oliver Hartwich is executive director of The New Zealand Initiative, a business think tank in Wellington.