The England international captain is close to securing his first Premier League title, as the Reds are currently five points clear at the top of the table with three more rounds of matches left this season.
"He's incredible - he's a good leader," Smicer told Liverpool's official website. "When we were playing and he was in the team, I knew that we had a far better chance to win the game than without him.
"Steven understands the game really well. He has changed his position, but his performances have got even better. I think with age you have to sometimes change your game. People were questioning whether he could still be at the top, but he's proving himself all the time.
"I am so glad that he is so close to winning the title and I just hope that they will finish this work and that Liverpool can win the title. He has won everything and [the title] is the only thing that he is missing."
Smicer played for Liverpool for six years between 1999 and 2005, winning the FA Cup, the Champions League and the UEFA Cup once each and the League Cup twice.