The now-Real Betis manager interrupted Moyes' West Ham tenure for a forgettable stint in 2018, and the Scot hit back with a vengeance.
Moyes was initially hired in 2017 as a replacement for fan favourite Slaven Bilic who had huge Dimitri Payet-inspired success and a seventh-place Premier League finish.
That made Moyes' first spell at the newly-opened London Stadium look rather underwhelming, with the former Everton boss seemingly still in somewhat of a malaise after his Manchester United experience.
When David Gold and David Sullivan got back on the phone in 2019, many were surprised, but four years on, he's on the brink of glory.
With a Europa Conference League final against Fiorentina on June 7, a first major trophy since 1981 could be on its way to the West Ham cabinet, and no one seems happier than Moyes who was literally jumping for joy after knocking AZ out of the semi-finals.
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That spell on the sidelines clearly helped shape the now 60-year-old, and so did finding a squad worthy of European glory.
A Europa League win last year was on the cards before slumping out at the semi-final stage with a very similar eleven of stars.
Chiefly among them are Declan Rice and midfield partner Tomas Souck, who have had a huge dose of flair added in the shape of £51million record signing Lucas Paqueta.
Things have also settled upfront with Said Benrahma locking in a spot next to Michail Antonio and Jarrod Bowen, while at the back £30m summer signing Nayef Aguerd is proving as big a hit as Paqueta.
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Comparing that to Moyes' first West Ham line-up in 2017, it's no surprise that his initial stint wasn't such a success.
Shepherded in ahead of the busy Christmas schedule, Moyes' first task was against Watford on November 19, and it was one that ended in an instantly humbling 2-0 defeat.
Will Hughes and Richarlison scored on that day, and didn't have much trouble getting through a sluggish midfield and defence.
Winston Reid and Angelo Ogbonna were paired at the back and flanked by Pablo Zabaleta along with the only remaining starter - Aaron Cresswell.
Ahead of them were Cheikou Kouyate, Pedro Obiang, Manuel Lanzini and captain Mark Noble, a quartet that doesn't quite scream the solidity and ball retention of their modern-day successors.
Behind them all was Joe Hart, but up front was where it got interesting.
Andy Carroll was in the midst of arguably his most successful club stint of his career, and partnering him was the ideal knock-down merchant, Marko Arnautovic.
The hot-headed Austrian was the Hammers top scorer for two consecutive years between 2017 and 2019 and became a household name before moving to Shanghai Port for the riches of the Chinese Super League in 2019.
But the most curious name of all in the squad that day was one that stayed on the bench - a young Declan Rice.
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With a handful of senior appearances to his name under Bilic, the now-England regular later became a permanent fixture under Moyes, playing every minute of their final nine games of the season.
Such form earned him three games for Republic of Ireland national team, showing just how much has changed since Moyes first rocked up in east London.