“…The body of literature analysing the UoO hypothesis provides inconsistent empirical results, and whilst some research supports the hypothesis (Peel & Thomas, 1997;Carmichael, Millington & Simmons, 1999;Wekli & Zlatoper, 1999;Falter & Perignon, 2000;Levin & McDonald, 2009;Schreyer & Torgler, 2018), the vast majority rejects it (Whitney, 1988;Knowles, Sherony & Haupert, 1992;Rascher, 1999;McDonald & Rascher, 2000;King, Owen & Audas, 2012;Coates & Humphreys, 2012;Coates, Humphreys & Zhou, 2014;Pérez, Puente & Rodríguez, 2017;Artero & Bandrés, 2018). Indeed, while these articles focus on a range of sports and therefore may yield differing outcomes, hitherto also within European association football the evidence is not conclusive (Peel & Thomas, 1992Forrest & Simmons, 2002;Goossens, 2006;Buraimo & Simmons, 2008, 2009de Groot, 2008;Michie & Oughton, 2004;Szymanski, 2001;Pawlowski & Anders, 2012;Scelles et al, 2013aScelles et al, , 2013bMontes, Sala-Garrido & Usai, 2014;Andreff & Scelles 2015;Caruso et al, 2017). Pawlowski (2013) suggests that empirical proof of the UoO hypothesis is absent because the proxies used to measure it are inadequate.…”