The Lions have been minimal spenders under Neil Harris but increased their outlay this summer following promotion to the Championship.
Aldridge, Millwall’s head of recruitment, said: “From the outside there is an expectation that every signing is going to be a success. But there was a study done of a 1,000 transfers in the Premier League from a couple of years ago and it worked out that about 50 per cent were what you’d consider successes – the rest failures.
“The average transfer fee now in the Premier League is £10million. There aren’t many other industries where a business regularly invests £10m and half the time that money doesn’t do what it was meant to do.
“The approach is becoming increasingly more scientific, structured and methodical – more logical. There’s a more business-like approach towards it in English football, and I include the lower leagues in that as well.
“In the summer after Leicester won the Premier League they spent £60million on six players – this is the same club that found Riyad Mahrez, N’Golo Kante and Jamie Vardy and won the Premier League off the back of their recruitment.
“By October-November last year the club were getting heavily criticised in the press for the
players they’d signed the following summer. It just shows that for as much planning and foresight you can put into these deals, there is an unknown element with every signing.
“At the higher end there probably is a correlation between spending and success.
“But if you look at our level we’re talking players on frees or comparatively small fees. It is very, very difficult to be absolutely certain.
“Every player we sign in the Championship – no matter how confident we are – is a gamble. There is that element of luck. There are lots of factors involved which can be injuries or players just don’t settle, that’s not saying they are bad characters.
“That is a reality across all the leagues. There is no perfect way of doing it. Some clubs are more heavily stats-based, we’re probably evenly-split in terms of the influence of video, statistics and eyes-on scouting. So far no-one has found the perfect or fool-proof way.
“We’re focused on reducing those errors but it is a case of small margins. If we can improve that efficiency by two, three or four per cent every year – year on year for five years – we’ll have made a significant difference.
“I don’t think individual transfer windows on their own can judge success and failure. It’s a long-term trend whether your signings do well or not.
“Neil does seem to have had success with try-before-you-buy situations. It’s certainly an easier sell to the board and the chairman when a player has already demonstrated his value in a Millwall shirt.
“I’d like to think the chairman feels more comfortable investing his money with the work that is done by Neil and ourselves on these players before we sign them.
“It adds a level of accountability, but also a level of due-diligence that wasn’t there before. If we get some of these right, logic would dictate we’ll be able to carry on cherrypicking players and spending fees here and there to slowly move the club forward.”