Saw an analysis on 538.com
today on how much incumbency is worth. Interesting point, Warren won by a large margin, 24 points, but she actually significantly under performed where statistics say she was expected to come in by over 14 points. Another take by CNN
using a different formula:
The Massachusetts secretary of state certified the state's US Senate election results this week and found that Democratic Sen. Elizabeth Warren defeated Republican Geoff Diehl by 24 points...
Warren's margin may sound impressive, until you realize Hillary Clinton won Massachusetts by 27 points in 2016. Clinton won by 3 more points than Warren, despite 2018 being a better year for Democrats nationally and Warren having the advantage of incumbency.
Warren's performance in 2018 was one of the weakest for a Democratic Senate candidate. I created a simple statistical formula explaining the results of the 34 Senate races with at least one Democrat (or independent who caucuses with the Democrats) and one Republican. Controlling for a state's weighted average partisanship and incumbency, Warren's performance was the sixth worst of all Democrats. She did 7 points worse than expected. (For comparison, Minnesota Sen. Amy Klobuchar and Vermont Sen. Bernie Sanders outperformed their baselines by 9 and 12 points respectively.)
Of course Massachusetts moderate Republicans might have found Diehl more palatable than Trump, but that should still give Warren pause.