Read Jerome Armstrong, who did some digging into the crosstabs. Essentially, the polls that show a close race are overestimating male turnout ... men haven't been 45% of the primary electorate in any state this cycle (Missouri was closest at 44-56).
I wouldn't call a 10 point win for Hillary Clinton a 'blowout'; the majority of contests so far have ended with 10-point or larger margins for one candidate or the other, and Clinton can in theory get as high as 58% of the vote but end up with only a 4 delegate gain. In practice, though, I think 8-10 delegates is more likely, which of course means Clinton will have to win an even higher percentage of remaining pledged delegates on April 23rd than she did on April 21st.
