Liberal Overreach at the Margin

It's inevitable that "liberal overreach" will be blamed for Democratic losses if they're large tonight and also blamed if they're small. But what I think overreach analysis always requires is more of a marginal approach.

For example, granting ad arguendum that the 111th Congress engaged in liberal overreach, which Senators who win today would have lost had the Affordable Care Act included a public option linked to Medicare? The answer seems to me to be nobody. Which Senators who win today would have lost had the 111th Congress passed a cap-and-trade plan through reconciliation? Here, it looks like Patty Murray. Would a "scaled back" health care plan have saved Blance Lincoln? Clearly not.