Redknapp wrote in The Sun: "Spending huge amounts of money on a striker doesn't guarantee you goals.
"Fernando Torres has proved that in recent seasons. But this year he has quietly been sneaking up the charts. He now has 19 goals this season - he is in the top five.
"The days of Clive Allen scoring 49 goals in one campaign are gone in England. Defences are much better organised and strikers really have to put in a shift off the ball as much as on it.
"If you analysed Clive's game, and I'm sure he won't be offended, he was no good in the air, had no pace and couldn't dribble one on one. Yet he was a superb finisher.
"These days that's not enough. Jimmy Greaves was a world-class marksman and could get 35-40 goals a year.
"But in the modern game it is even harder to score against defenders who are quicker and more comfortable on the ball.
"So, 19 goals from Torres is a good return. If you have a striker on your books who gets you 20 goals per season then you have to be satisfied."