Ultimately coaches do bear the responsibility of wins and losses over the long haul, fair or not, but I do kind of agree with OP. I thought the coaches put the players in a position to win had they executed. I feel the same way about Northwestern game. I don't think Sean Tyler is coached to fumble the ball, I don't think Nubin was coached to take horrible angles on those two long touchdowns, I don't think Athan is coached to sail the ball over his TE's head, etc.
We all want to look for explanations and someone to point fingers at after a devastating loss, but the reality is sometimes you just lose, plain and simple. We could argue for years over who's at fault, but Illinois made one more play, got one more bounce, made one more block, one more tackle, etc. Two evenly matched teams played a close game that was decided by one point in the last minute. There's not always a simple explanation to why we lose.