Yeah, that charts who's most likely to win a majority of delegates, not just "win." There were so many candidates a month ago, gaining more than a plurality was more or less impossible. Bernie was in the lead for a while, but duking it out with "Nobody" (AKA brokered convention) at the top.

As more contests have happened and everyone has dropped out, it's become more obvious that Biden won't just have a plurality, but will have an actual majority.