#3 Gerardo Tata Martino | Barcelona manager
After earning a good reputation as a manager with dexterity in the Argentine domestic league, Tata Martino made the move to Spain to manage Barcelona in 2013. His style of play with Newell's Old Boys attracted the higher-ups at Camp Nou, but his one-year stint with the Bluagrana didn't reach expectations. In Martino's defense, Barcelona started off the season with brilliance and wins, but things went south sooner rather than later.
Although Messi played well under Tata Martino's management, scoring 41 goals in 46 games was notably the star's lowest goal output per season since 2008. However, the manager couldn't get Barcelona to any trophies that season, apart from a Supercopa de Espana at the beginning of the campaign. Losing the league title to Atletico Madrid and crashing out of the Champions League, also thanks to Atletico, was too much for Blaugrana to bear. Martino was later sacked that season.
#2 Ronald Koeman | Barcelona manager
As much as Ronald Koeman did his best to right the flailing ship that was Barcelona, Lionel Messi notably left the club under the Dutchman's tenure. Koeman struggled to fix Barca's problems on the field, but it was hardly going to be an easy task. When he entered after Quique Setien was sacked, the former defender had to deal with Messi's transfer request, alongside a demoralized squad.
To be fair, Koeman did steady the club somewhat, eventually winning the Copa del Rey, but their financial doldrums pushed Barcelona into turbulent waters. The club were unable to keep Messi at Camp Nou, eventually letting him go on a free transfer. Koeman couldn't string wins together, with the squad left in disarray after their beacon had left the team. It all culminated in the Dutchman's sacking, with another club legend, Xavi Hernandez, taking over the reins.
#1 Quiqie Setien | Barcelona manager
The former Real Betis manager is regarded, by Blaugranes, as one of the worst managers in Barcelona's expansive history. Managing the side from January to August 2020, Quique Setien took charge of only 25 games. The club notably fired him just three days after losing 8-2 to Bayern Munich in the Champions League quarter-finals, putting an end to a troubling managerial tenure. Barcelona notably ended the season without a single trophy, having been kicked out of the Copa del Rey by Athletic Bilbao, with Real Madrid winning La Liga.
2020 is popularly regarded as the year Robert Lewandowski would've won the Ballon d'Or if it had held, with Lionel Messi hardly in contention. Messi's 31 goals in the 2019-20 season was the star's lowest output since 2008, and he looked rather intent on leaving Barcelona. One could argue that Setien joined Camp Nou in January, which hardly gave him time to gel with an already struggling Blaugrana outfit. However, the eight goals conceded against Bayern Munich- Barca's worst in 74 years - will make Setien's tenure unforgivable and unforgettable.