Despite being the Whites’ standout attacking threat for much of this season, the winger was benched at Elland Road, and was only introduced into the action at half-time with his side already 2-0 down.
Raphinha helped to make an instant impact, scoring the second in a quickfire double that brought Leeds level, but Bielsa’s men were ultimately undone by late strikes from Fred and Anthony Elanga.
Reflecting on the South American’s initial omission from Bielsa’s plans, Crooks expressed his disdain for the decision.
Speaking to BBC Sport, he said: “I have very little time for any manager, especially with limited resources, who leaves their most talented player on the bench against a top-class side and still expects to get something out of the game.
“In the first half, Leeds were like lambs to the slaughter playing Manchester United.
“How you leave Raphinha on the sidelines against a team like United beggars belief.
“Bruno Fernandes on the other hand played throughout in very difficult conditions and was outstanding. He covered every blade of grass, scored a brilliant goal and demonstrated just what top-class players have to offer.”
Raphinha’s strike against Man United was his ninth in the Premier League this season - a tally that makes him Leeds’ top scorer by a comfortable margin.
The Whites’ next most prolific player this term has been Jack Harrison, who has registered six goals in 24 top flight appearances.