Tony Pulis pointed towards missed chances as Albion crashed out of the FA Cup in the quarter finals.
Brown Ideye missed two first half opportunities to give the Baggies the lead during an impressive 45 minutes for the visitors.
But after Albion had fallen behind, Joleon Lescott wasted a free header to equalise before the Baggies conceded a second after Claudio Yacob's harsh red card.
"Hutton should have been sent off in the week," added Pulis.
"He didn't and gets the cross in that Foster spills.
"And today wasn't a sending off. It's two poor decisions.
"Yacob had three touches before the ref blew up. Initially I though the linesman had said something but Anthony told me it was his decision."