It can be argued that we witnessed the end of an era, one in which José Mourinho could be marked out as a coach who got both top-quality defending and attacking from his players, which possibly arose from Chelsea's Champions League defeat to a 10-man Paris Saint-Germain in the 2015/16 season. The Portuguese's team proved unable to adapt to what that last-16 second leg demanded of it.
Since then, his sides have been able to defend with the best of them, sure; but his insistence on leaving the men up front to rely on attacking instinct, rather than order, has grown obsolete.
And Tuesday's elimination at the hands of Sevilla, also in the first knockout round of the Europe's top club competition, could well prove to be the final nail in the coffin for the reputation Mourinho has enjoyed in English football of being at the leading edge of the coaching elite. He will continue to occupy the dugouts of major clubs (he has just signed a new contract with Manchester United, and we may well see him at PSG in the future), but an excellent Sevilla exposed United's lack of clear ideas with the ball; the Red Devils were stuck far too far within their own shell.
In the final 10 minutes, we saw the United that might have been; but the fact is that Mourinho has never felt comfortable giving free rein to talent and an, at times necessary, element of disorder.