Not for the first time this year the media has considered the perverse effects of playing in the Europa League. Today, Sky Sports reported “there has been a remarkable improvement to Liverpool and Tottenham's results [in the EPL] since their last European ties on December 11 and 12”.
It's commonly insinuated that playing in the Europa League causes a ‘hangover’ and that juggling two competitions influences domestic performance. Taking account of all the data since the beginning of the Europa League competition in the 09-10 season, it becomes clear that English teams that reached the group stages of Europa League have actually won more domestic matches three days later following a Thursday night match.
While I don’t control for the standard of opposition here (as Europa Cup entrants are usually above average performers), the location of the EPL match, or compare post Thursday results to the rest of a teams results, the aggregate stats on an issue that has an important temporal component suggests that there’s not much in the 'hangover' idea. At best there may be some weak effect going on.