Arsenal were closely linked with re-signing former attacker Carlos Vela in the summer, but elected to allow him to stay at Real Sociedad.
The Gunners had the power to bring him back to the club by invoking a buy-back clause in his contract at just £4 million, instead they pulled off a masterful deal which saw Sociedad pay them £12 million just not to do so.
Vela, 25, penned a new deal and after a slow start to the season has really hit form. He has six goals and two assists even with the Spanish side struggling for form.
He helped David Moyes' team beat Barcelona at the weekend, and his star continues to grow, according to a new study.
The CIES Football Observatory have listed their transfer values for players and assess Vela to now be worth 27 million Euros.
This converts to £21 million, and suggests while Arsenal may have pulled off an astute piece of business - Sociedad will probably feel the same way that they have paid a bargain to secure a player who is an important part of their plans.
The survey values Vela among some big name players, including Swansea's Wilfried Bony, who they claim is worth €25 million. Tell this to his club of course, who want to charge Manchester City closer to £30 million.
Also valued at the same price as Bony is Liverpool's Daniel Sturridge, and Arsenal's Olivier Giroud €24 million. The full report can be read here.
Vela may feel he made the right choice staying put, judging by the lack of football Joel Campbell has experienced at Arsenal this season.