Messi left Barcelona last summer to sign a two-year deal with PSG. However, since moving to France the seven-time Ballon d'Or winner has scored only two goals in Ligue 1 and five in the Champions League. He was on the team that gave up a two-goal advantage to lose to Real Madrid in the Champions League round of 16 and was then booed during the next game, against Bordeaux.
Alves, who is in his second spell with Barcelona and has helped revitalise them under the management of Xavi Hernandez since rejoining in November, questioned Messi's mindset.
"Messi is not enjoying himself," Alves told ESPN in an interview that took place before PSG's Champions League elimination against Real Madrid. "For me, he's out of place. Right now, Leo is out of place there. Leo always said to me: 'Where could I be happier than here?'
"I'm proof of that. There's nowhere better than here. For whatever reason, Leo isn't here today but I hope he can come back."
When asked which young player has surprised him the most Alves answered Pedri and said the 19-year-old brings to mind Xavi when he was a player.
"[He reminds me of] the manager," Alves said. "He sees things others can't see and he does things others can't do."