#3 Ernesto Valverde

Barcelona suffered a humiliating defeat at the hands of Real Madrid in the Spanish Super Cup at the start of the season. Fast forward, none of the Catalans in their wildest dreams might have expected their beloved their club to dominate the league like never before.
Ernesto Valverde, the man at the helm at Nou Camp, guided Barcelona to the La Liga title with 27 wins, 9 draws and just 1 loss under his belt. Sounds even more impressive, considering how the Catalan club had a considerably disappointing transfer window.
Even with Neymar sold and Dembele injured for large part of the first half of the season, Valverde's men cruised to victory after victory as the Madrid clubs faltered in their wake. The Spanish coach introduced a 4-4-2 system and produced wonders with a rather mediocre midfield. He scrapped the 4-3-3 and once again built a team around Lionel Messi with the Argentinian producing outstanding performances week in week out as usual.
However, as much as having Messi brings positives to any team, the 'Messidependencia' is a disease tough to stop. That's what Valverde and co fell prey to; Barcelona relied too much on the forward to deliver in times of need. The one game in which he didn't perform, Barcelona said goodbye to the Champions League after bottling a 3-goal advantage against Roma in the Champions League.
If it wasn't for their disappointing UCL campaign, Valverde would have been higher on this list, thanks to his heroics in the La Liga.