Diangana, who had a taste of senior football at West Ham last season, had scored or made seven goals in 10 games for West Brom prior to Tuesday's visit of Barnsley.
But the 21-year-old failed to add to his tally as the Baggies were held to an unlikely 2-2 draw by the bottom-of-the-table side.
And according to some of a West Brom persuasion, Diangana was particularly off-colour - although not everyone was quite so critical of the West Ham academy product.
This is what they have had to say on Twitter...
Slav gonna bring on Austin and Diangana at any point?— Grant (@grantharrison91) October 22, 2019
Edward's, Ferguson, Pereira, Austin, Diangana. All woeful tonight #wba— Baggies Burger (@BaggiesBurger) October 22, 2019
Strange first half that. #wba look rattled by Barnsley, who’ve been time wasting since the 15th minute. Edwards has been poor, tackled himself twice. Pereira and Diangana haven’t turned up yet. Furlong looks the best outlet. Early goal is an absolute must in the second half.— Alex Apati (@LadsAlex) October 22, 2019
Truly appalling half of football. Defending like kids and not a shot in 49 mins against a team who has the worst away record in the Divsion. Pereira, Edwards, diangana & Austin (as per usual) contributed nothing— Gee to the Bee (@Baggieglenn) October 22, 2019
Yeah Diangana really struggled, wasn’t his night at all. Although he was miles better than Edwards— Ashley Burtoft (@AshBurty) October 22, 2019
Player ratings 'IMO' :— Luke Rowland (@LukeRowland015) October 22, 2019
Livermore 8 *MY MOTM*
Edwards 2 (give him time)
Pereira 7 (lucky he scored the goal cos would be 5)
Krov 7 #wba
Couple of positives, and a lot of negatives about last nights performance. The whole team looked lethargic, Diangana was playing as though he was carrying a knock. You begin to imagine where we’d be with a striker who can get in behind and find the net. Dwight Gayle for instance.— Jamie.Theo (@JamieTheo2) October 23, 2019
Grady was having a shocker tbh— R. Smith (@Albionwestand) October 22, 2019
Diangana the only one that looks arsed— Thomas The Skank Engine (@Rollsie7) October 22, 2019
Diangana off - Shambles— Ben (@BxnAdams) October 22, 2019
Diangana is due to spend the rest of the season on loan with West Brom, although unconfirmed reports suggest that a January recall may be possible.
West Ham have plenty of options in the Congo-born player's position, including their high-profile summer recruit, Pablo Fornals.
West Brom fans - is Diangana's latest display of any concern to you?
Have something to tell us about this article?