The reigning champions were made to work hard by last season's 14th-placed side, only putting the game to bed with a couple of goals in the final seven minutes.
Barca boss Valverde feels that Alaves's defensive approach at Camp Nou did not help his side, but is hopeful that there will be more rounded team displays to come.
"We haven't been able to play our best game," he said post-match. "The fact that they were situated so deep made our first combinations slow down a little.
"They had very tight defensive lines, a very defensive approach, and it made things difficult for us, but we're in August and hopefully we'll improve."
Barca travel to Real Sociedad in six days' time for their next league outing.