Having been left with only Luis Suarez as a regular striker when the last transfer window closed, Rodgers moved quickly in this one to supplement his forward options.
Sturridge is an England international. But his four caps equal the number of clubs he has played for, with a period on loan at Bolton in addition to spells with Manchester City and Chelsea prior to his big £12million Anfield move.
He could start alongside Suarez in Sunday's eagerly-anticipated Old Trafford showdown, but Ferguson feels his ability cannot be taken for granted.
"The big issue for Liverpool is whether they include new signing Daniel Sturridge," Ferguson told United Review.
"Certainly the arrival of Sturridge gives Brendan Rodgers more strength and options up front.
"Sturridge has had a few clubs but I don't blame him for jumping at the chance of joining Liverpool because he just wasn't playing regularly with Chelsea and I always rate a player whose priority is wanting to play.
"Even so, his track record moving between a number of clubs suggests Brendan Rodgers is taking a bit of a gamble, but he clearly knows what he is doing."
Ferguson has selection issues of his own to deal with, not least whether to draft Nani and Anderson straight back into his starting line-up after recovering from their respective hamstring strains.