Probably no one in Europe knows how good a manager Ricardo "Tuca" Ferretti is.
Ferretti has led Tigres to the last two Liga MX titles. He has never managed outside of Mexico, with stints managing Chivas Guadalajara, Toluca, Morelia, Pumas and three different spells at Tigres. He has Mexican citizenship, despite being Brazilian by birth.
During his latest stint at Tigres, he has established the club as the best in North America despite being under-resourced compared to the competition (looking at you, Club America). He's the only manager to win five titles in Mexico's short-season era and managed the Mexico National Team, in addition to his Tigres duties, in the aftermath of Miguel Herrera's firing while the Mexican Football Federation searched for a replacement. He beat the USA in the CONCACAF Cup playoff and drew with a full-strength Argentina side.
He's 62, so he'll probably finish his career at Tigres, but he might be worth a flyer for a European team down on its luck. If he never gets a chance to manage on a larger stage, it will be a shame, but maybe he doesn't care.
Ferretti has had a remarkable career, and beating Club America in the Liga MX final on Christmas is the icing on the cake.
If someone in, say, Spain discovers Ferretti, Tigres will have lost someone irreplaceable.