Barca signed the Chile international from Italy's Udinese last year for a deal including variables that could rise to some 37 million euros, but he has yet to really make his mark at the Nou Camp.
"We haven't seen the best of Alexis yet," the 23-year-old told a news conference.
"I am finding some form and as each game goes by I am improving a little more."
Alexis was Barca's second-highest scorer behind Lionel Messi in La Liga last season with 11 goals, but suffered a string of niggly injuries in his first campaign.
"I need to get into the games more and take people on in one-on-one situations," he said.
"I know I can win a place. Step by step I am making my name here because I am Alexis. I would rate myself with a five [out of 10]."
They top Group G after last week's 3-2 home win over Spartak Moscow.
