Moran appeared as a second-half substitute at San Mames just two hours after attending his father's funeral, who passed away on Friday.
"Erik demonstrated a lot today and he wanted to be here," Valverde told reporters at a press conference.
"After the match I told the locker room that Moran is a champion and we all have a lot to thank him for. We needed him and he has always been available despite such a complicated situation."
Moran, 22, has been with Bilbao since 2004.