Despite Hillary's wins yesterday, Bernie performed impressively
I think Bernie lost Ohio by a wider margin yesterday in part because of Kasich and Trump crossover votes, the semi-closed primary system (which requires being registered to vote 30 days in advance, preventing last minute voter enthusiasm for people who aren't registered to vote) and because of early voting (which started on February 17th), which favored Hillary because Bernie wasn't known as much yet.
Just look at the polls vs the result:
Ohio:
Before March 4th: Hillary averaged +20
After March 4: Hillary averaged around +7
Ohio result: Hillary + 13.8
Illinois:
Before March 7: Hillary averaged around +35
March 7th and after: Hillary averaged about +5
Result: Hillary won by only +1.8, and this at her home state!
Missouri
Wasn't heavily polled, the only two polls on RealClearPolitics shows one with Hillary +7 and Bernie +1, final result was a virtual tie.