The Chilean joined Barca from Udinese in the summer of 2011, but has so far been unable to replicate his scintillating Serie A form for the Blaugrana, prompting rumors of a potential exit from the club.
Valdano believes the 24-year-old could be affected by playing in the shadow of talisman Messi, telling Radio Cooperativo: "Alexis seems to be missing confidence. He always used to have a lot of flair and took on opponents. Now he seems to prefer the safe route and pass to a teammate.
"Maybe Messi's presence overwhelms him. You don't know how the mind of certain top players works. I still remember Ariel Ortega at Valencia. He used to do very well, but then Romario came onto the scene and Ortega just went missing all of a sudden."
Alexis has made 54 La Liga appearances so far for Barcelona, scoring 20 goals in the process.