Wow, She Really, REALLY Cannot Act....
Reading some of the reviews from the play she was doing in London and they are awful:
http://www.broadwayworld.com/article/Review-Roundup-MCQUEEN-Starring-Stephen-Wight-and-Dianna-Agron-Opens-at-the-St-James-20150520
"That actor Stephen Wight should wring a tender portrait of a troubled man out of such crass writing, surrounded by tech and opposite the expressionless void of co-star Dianna Agron ("Glee"), is nothing short of a marvel...Agron, however, is little more than a clothes horse. She plays up Dahlia's numbness and ends up vocally monotone, facially inert and deeply unwatchable."
It's not surprising because she can't even act on screen even with the opportunity to do multiple takes. What made her think she was at all capable of acting on the stage with her many talent deficiencies and lack of charisma? How embarrassing.