Although FBM replacement values are not meant to predict future transfer fees, it was noticed by many people that often the FBM replacement values of a player were much closer to the actual transfer fee than the valuation listed on TransferMarkt. For that reason we counted in how many cases FBM transfer values were closer to the actual transfer fee than the valuation on TransferMarkt.
DM request: Oscar Fraulo (2003) is a fantastic CM, a superstar in the making. You have seen me complain about CMs a lot, but Fraulo sets the standard on CMs. Maxed out finishing & passing game probability with decent defensive probability as a nice bonus. pic.twitter.com/zPixY4leYz— Joost van der Leij (@JoostvanderLeij) May 17, 2022
A group of 1631 players were chosen by other people. This meant we had no influence on selecting which players we looked at. Of those 1631 players 159 had a transfer that would be counted. Transfers that followed loans and transfers in exotic leagues were excluded.
Of those 159 transfers in 108 (67.9%, p-value < 0.001) cases FBM transfer values were closer to the future transfer fee than the valuation at TransferMarkt. That makes FBM replacement values a more reliable source for future transfer fees than TransferMarkt.
Nevertheless, that doesn’t mean that either TransferMarkt or FBM replacement values are a good predictor of future transfer fees. One can see that in the fact that the average transfer fee in this group was 13.25M and that TransferMarkt on average was off by 4.5M or 34%, while FBM replacement values were on average off by 4M or 30%. In 65 or 40% of the cases FBM transfer values came out exactly right, whereas TransferMarkt only had it exactly right in 7 or 4% of the cases. One can check all transfers here oneself. Please note that we make a distinction between win/win deals where the transfer fee is higher than the replacement value of the player for the selling club, but lower than the replacement value of the buying club on the one hand. And bad deals where either the selling club sells for less than the replacement value of the player for the selling club, or the buying club buys for more than the replacement value of the player for the buying club, or both.
Comparing FBM replacement values to TransferMarkt
Of course, FBM replacement values have one big advantage over the valuation at TransferMarkt and that is that FBM replacement values are actually a range rather than a single number. It is much easier to predict future transfer fees with a range than a single number. Nevertheless, we stand by this approach as in our philosophy it is a bad idea to think that a player has a single fixed value. Instead, we think that every player has a different value depending from which team’s perspective you look at the player. FBM replacement values mirror this idea that players are more valuable to some teams and less to others.
TransferMarkt also has advantages. Because TransferMarkt relies on rumor, knowledge of contracts and years left on contracts, they can and do quickly update as soon as news of a transfer breaks. For that reason, we have taken the previous valuation. This hardly makes a difference as the rumors are wrong in about half of the cases this applies to. FBM replacement values are 100% calculated. This makes it in principle more difficult to compete with human knowledge of transfers. Nevertheless, the 100% calculated FBM replacement values outperform TransferMarkt. We are currently not applying our FBM transfer model to calculate the probable stats of the player at the new club in these cases. Because of that it is highly likely that if we were to do so that the FBM replacement values would be even more precise so that the percentage where FBM replacement values lie closer to future transfer fees than the valuation at TransferMarkt would be even higher.
Validation of the FBM player statistics
Because the FBM player statistics play a big role in the calculation of the FBM replacement values, the fact that FBM replacement values are in 2 out of 3 cases closer to the actual actual transfer fee than TransferMarkt, also validates those FBM player statistics indirectly. For if the FBM player statistics would not be correct, then it would be highly unlikely that the FBM replacement values could be more accurate than TransferMarkt.
Lisandro Martínez is a very good CB. Maxed out finishing probability with very high passing game probability. Great for building up from the back. Replacement value for @AFCAjax = €20,058,325. Martinez will hard to replace for Ajax. pic.twitter.com/CPRevgCgcT— Joost van der Leij (@JoostvanderLeij) June 21, 2022
As a way to validate FBM player statistics and FBM replacement values even more, we predict that in cases where the actual transfer fee was at least twice as high as the FBM replacement value for the buying club that this player is going to disappoint in the coming season. This disappointment doesn’t have to be that the player is performing badly. It could well be that he performs adequately, but that given the amount that was paid for him, people feel that he is a let down.