And it ended with his season-long loan being cut short as soon as they crashed out of Europe.
There was also a criticism of a cautious style of play, according to a close Marseille watcher.
The Denmark international is now back with Albion looking ahead to the final months of the season.
His loan was cut short on deadline day and he can now add to his two early-season outings in the Prem.
O’Riley generally played in a central midfield double act with international colleague Pierre-Emile Hojbjerg in his time playing for Roberto De Zerbi’s OM.
There was also some time in the No.10 role he has been handed at times by Fabian Hurzeler.
Ludovic Ferro, of La Provence newspaper and website in Marseille, said: “He had three excellent games in September, October so everybody thought he was a great player.
“Those games were against Paris, victory, Ajax, victory, and Metz, victory.
“Maybe the best period for Marseille too, this season.
“After that he was never terrible but very neutral.
“Without risk in this game, not enough key passes and too many apsses back or sideways.
“Sometimes it’s good to build the game but he was not good enough.
“He lost his place as a starter in maybe November and after it was it was finished.
“He missed a penalty against Paris St Germain in our Community Shield in January so not a good stay in Marseille.”
Marseille still looked set for a Champions League play-off spot going into the two final rounds of fixtures.
Then a 3-0 defeat by Liverpool, the same result away to Club Brugge and Benfica’s late goal against Real Madrid dumped them out.
O’Riley was an unused sub on Satrday as OM let slip a 2-0 lead to draw 2-2 at lowly Paris FC in the league.
Ferro said: “In Marseille we are really impatient and here, if you are not good in three months, they can sell you or break your loan like now with O’Riley.”
Other than French Cup ties against lower division minnows, O’Riley has not played more than 45 minutes in a game since facing Atalanta on November 5.
He played the full 90 minutes in the win over PSG which sent title hopes soaring early in the season.
And his only goal came in the aforementioned 3-0 win at Metz.