"Sometimes when you bring in a player on a Bosman they turn out to be worth their weight in gold," McAllister, who also excelled at Liverpool after signing on a free, told LFC Magazine.
"Rafa won't need to spend a lot of time telling someone like Voronin what to do. A player of his experience and ability knows instinctively when to move and where to run to.
"You can tell just from a few performances already that he is very assured and knows exactly what he is doing. He reminds me a bit of Teddy Sheringham with his eye for a pass and the positions he takes up.
"Players like Fernando Torres and Ryan Babel represent buying potential. These players will only get better and better every year they play in the Premier League with better players around them. The manager will then add to these as he goes along.
"On the other hand, players like Yossi Benayoun and Andriy Voronin have arrived as experienced international footballers who have been around for a while. These are always valuable players to have at your disposal."