The Argentina forward played a crucial role in his side's run to the final, scoring four goals and recording one assist.
However, Messi struggled to truly impress against Germany in the showpiece decider on Sunday night, as the Europeans saw off their opponents with a 1-0 victory after extra time.
"His performance was poor tonight," Collymore told talkSPORT. "We've seen him three or four times now in the flesh and he's been poor in all of them, bar several trademark runs which I think masks a lot.
"He wasn't even the best player in the Argentina side tonight or over the tournament, [Javier] Mascherano gets that vote for me."
Meanwhile, Manuel Neuer was rewarded for a fine tournament display with the Golden Glove accolade, while Paul Pogba won the Young Player Award.