Aldridge said: "It was no surprise to see Xabi Alonso's return from injury add an extra dimension to Liverpool's play at Sunderland.
"Momo Sissoko and Didi Hamann are terrific at protecting the defence but they haven't got Alonso's passing ability. When he is in the starting line-up, we look a much bigger threat.
"The balance of Alonso in the middle and Steven Gerrard on the right is perfect because they are in tune with one another. Just look at the way they linked at the Stadium of Light.
"Liverpool's form dropped away badly last year when Xabi broke his ankle but if he steers clear of injury this time around, he will be a hugely important player in the second half of the campaign."