Robin Van Persie may be one of the greatest ever signings for Manchester United. He definitely falls into the "Marquee" category. Rio Ferdinand was also a marquee signing when he joined in 2002 for the equivalent of €42 million, including add-ons. He and Thiago Silva are the most expensive defenders ever.
But Nemanja Vidic has turned out to be one of United's greatest bargains, initially costing the current equivalent of only €9 million in 2006.
For the last eight months or so, Sir Alex Ferguson must have hoped and prayed that his star defender and club captain would return fit, well and raring to go. Vidic has eased himself back in, but has looked his old competent self from the first minute of his pre-season warm-ups.
Putting a value on Vidic
OK, so he's 30, but Thiago Silva is 27. It'll be interesting to see who goes on longest. He went to PSG for €45 million, equivalent to £35 million.
As to who is better, my vote would still go to Vidic. I watched all of Brazil's Olympic matches and was at Old Trafford for the semi-final and Wembley for the Final.
The Brazilian defence looked suspect throughout and as captain, Silva must take some responsibility for their ordinary performance against a well-organised Mexico side in the Final. Certainly, many Premier League sides would fancy a crack at their centre backs and keeper.
Another full back, Fabio Coentrao moved from Benfica to Real Madrid for €30 million in 2011 and Dani Alves to Barcelona in 2008 for €35.5 million.
So we're not talking about Vidic's current market value, we're talking here about "opportunity cost."
How much would Vidic cost to replace?
Of course you would go for a younger man, because no top club will buy a 30-year-old defender. We saw what happened with Laurent Blanc, though he was only a stop-gap.
Manchester City are reputed to have bid £20 million for Daniel Agger, which was turned down flat. Because of the consequences, Liverpool would surely not let him go for much less than £30 million. He is 27.
Mats Hummels is much younger, but again, having sold Shinji Kagawa to United, surely they wouldn't let a player—good enough to interest Barcelona—go for much less than £30 million. Thomas Vermaelen would surely command a similar fee.
Vidic's worth to United
So leaving the academic arguments aside, what is Vidic's return worth to Manchester United?
There can surely be no doubt that his injury cost United the title last season for many reasons.
First, there was a need to build a new partnership, because even at United, you need stability in defence. The jury was out on Jonny Evans, especially after his sending off against City. Rio Ferdinand had a history of back troubles and apparently couldn't be relied on for two matches in a week.
Chris Smalling, having shown excellent promise in his first season, was still green at centre-back, though impressive at right back. Phil Jones was just signed at 19, as a development project for the future.
In the event, there was also a catalogue of injuries and once again Michael Carrick had to be drafted in as emergency centre-back.
So Vidic's loss was much more catastrophic than it seemed at first sight.
Eventually the Ferdinand/Evans partnership was established and the latter transformed his fortunes to the extent that some fans thought he should have been Player of the Year for United.
And Rio Ferdinand was Lazarus reborn.
So this season, it is not just about feeling like you've got a new signing; it is about the re-establishment of the Vidic/Ferdinand partnership for one last hoorah.
It maybe only for one season before Rio becomes a squad player, but that should be enough time for at least one of the three "understudies" to establish their claim beyond question.
In fact—why not all three?
And for that matter, there are also the young pretenders. In a year's time, Michael Keane, Tom Thorpe, Tyler Blackett, Scott Wootton, Michele Fornasier or Sean McGinty may be laying down a challenge, to name just six young contenders at the club.
So if Vidic and Ferdinand play together for most of the matches this season, we can expect stability and security in defence, with added bonuses, apart from clean sheets.
David De Gea will be even better with a rock solid defence in front of him and the whole team can express itself in the traditions of United, knowing that there's somebody at home behind them. Patrice Evra can continue to maraud as a wing back, knowing that the dynamic duo will clean up behind him. Rafael and others who come in at either full back position will develop faster.
Finally, let's not forget that Vidic is club captain. He leads by example, is a calming influence, gets the crowd going with his fearless defending and scores goals.
Best of all, he and Rio make other players look and play better.
The proof of the pudding
Let's start with some comparisons:
Hummels and Subotic: the established partnership at Dortmund conceded 25 goals in 34 matches at 0.74 per match.
Vermaelen and Koscielny: conceded 49 goals in 38 matches (1.29) in the EPL.
Agger and Skrtel: 40 in 38; 1.05
Kompany and Lescott: 29 in 38; 0.76
Luiz and Terry: 46 in 38; 1.21
In 2010/11, the last time Vidic and Ferdinand played together for a whole season, their stats were: 37 in 38; 0.97
But in 2009/10, United conceded 28 in 38 (0.74); 2008/9, 24 in 38 (0.63); 2007/8, 22 in 38 (0.58); and 2006/7 27 in 38 (0.71).
So, in the five full seasons they have played together, United have conceded a total of 138 goals in 190 EPL matches, at a rate of 0.73, better than Kompany and Lescott, the best central defence in the Premier League last season.
What you cannot quantify, however, is what would have been the result of the two matches against City, which United lost by six goals on aggregate.
Vidic was banned for the first match and instead of Evans, who got sent off, or Smalling, who let Kompany score in the return, surely United would have got at least a draw out of one of those and the title would have stayed at Old Trafford?
During the five year period referred to above, United won the Premier League four times and the Champions League.
Last season, Vidic injured his knee early in the final Group match of the Champions League, which they went on to lose 2-1. If Vidic had not been injured and they had won or even drawn that match, they would have qualified for the knockout stages.
The financial difference would have been an estimated £20 million, even if they hadn't progressed beyond the first knockout round.
And that, together with the difference between first and second place in the Premier League can have a material effect on broadcast revenues.
There were all sorts of rumours flying around at the start of the transfer window about centre-backs that United might be interested in. At that stage, it was not certain that Vidic would return at all, let alone fully fit for the new season.
His return to match fitness is a massive boost. Even without the injuries to Smalling, Evans and now Jones before the season starts, there would have been the challenge of a settled partnership at centre-back, which in any case would be unlikely to achieve the meanness that Ferdinand and Vidic have become world famous for.
The captain's return feels like a new signing and, if United go on to win the EPL and/or the ECL, the financial benefits will be massive and the bragging rights immeasurable.
If, as I believe, Robin Van Persie turns out to be a steal at £22 million, then surely Vidic's return is worth £35 million over the remainder of his contract.