Was Lionel Messi the world's best player in 2008 before Pep Guardiola arrived? Yes. Was he this unstoppable all-conquering juggernaut, hailed as one of the best players ever to kick a ball? No way.
Lionel Messi used to score 15-17 goals before Pep arrived. Under Guardiola, he has scored an absolutely unbelievable 138 goals in 159 matches, not to mention his 53 assists. If he was already the world's most dominant player and finest dribbler before Pep arrived, under the latter he also became the world's greatest goalscorer and provider.
He has become so good that even Pep stated that he feared Leo becomes bored, since he's so far ahead of his peers.
But Messi himself admits that his current status has a lot to do with Pep Guardiola. From his first day, Guardiola tried to find the best set-up to fully maximize Messi's potential, and the results are apparent: the Argentine is widely acknowledged as this generation's greatest player and is only a few months away from winning his third consecutive Ballon d'Or. Given the huge gulf between him and the rest, he's likely to win even more.
Messi once claimed he wouldn't be the player he is today without Guardiola, and he was clearly being sincere. Pep Guardiola's managerial career will forever be associated with one of the greatest football players of all time, Lionel Messi.