Simson, who was appointed in late 2019 and held the energy portfolio, remained a fairly low-profile figure despite the European energy crisis which struck during her tenure, POLITICO said. This may have been in part due to key aspects of her role being "hoovered up" by ex-Green Deal chief Frans Timmermans and Maroš Šefčovič, Timmermans' successor, as well as by von der Leyen herself, POLITICO added.

Of positive aspects, POLITICO pointed to Simson's advocacy of greater support for Ukraine's beleaguered energy grid in the face of the Russian invasion starting in February 2022. She was also "able to chart a course through stacks of complex legislation without any major crises," the publication added.

The European Commission's leadership under Ursula von der Leyen, 2019-2024, has been marked by both successful responses to crises and struggles with internal challenges.

POLITICO gave von der Leyen a grade B minus in her handling of the war and the COVID pandemic, among other episodes. Von der Leyen was this year reappointed to a second term as European Commissioner.

Meanwhile, Kaja Kallas' predecessor as High Representative of the Union for Foreign Affairs and Security Policy, Josep Borrell (Spain), also only garnered a grade C. Despite his "notable" support for Ukraine, his performance in other foreign relations areas, including the Middle East, was "mixed," the publication said.

Of other commissioners from Estonia's region, Finland's Jutta Urpilainen only managed a C minus, Valdis Dombrovskis of Latvia a little better at C plus, while the Lithuanian commissioner, Virginijus Sinkevičius, who held the environmental portfolio, did best, at A minus.