Given that Clinton very publically targeted suburban Republicans (without much success), it seems more a case of her dragging down the whole party.
Isn't that always the question though? Did somebody win because they were a good candidate vs. winning because they ran against a poor candidate.
There were other tests we saw in 2016 that showed either progressives didn't show up or weren't a large segment. California's prop 61 failed, as did single payer in Colorado and a noted progressive in Feingold lost in Wisconsin of all places (even losing the 18-24 year olds to his republican opponent).
If Clinton brought down turnout among progressives because she spent too much time and energy courting moderate republicans then it kind of goes to show that the GOP have an advantage with ginning up turnout. The GOP didn't need a good candidate to save their senate and house majorities (as evidenced by swing state senators and he House GOP outperforming Trump) whereas the Democrats do apparently need a good candidate to gin up turnout for both their down-ballot measures and candidates.
Again context is important. You can't pick & chose data here. Minimum Wages hike won huge in ballot measures. Marijuana won big in ballot measures. Coloradocare failed because close to half of the party (Clinton/Obama wing) didn't want to abandon the ACA (The Gov, Senator came out against it, they were Dems). And it was worded poorly & financing was also not done well. There were some taxes on seniors & so on. I know many diehard Bernie supporters who opposed Coloradocare in its present form. And state wide Single payer is probably harder to implement for a smaller state especially when Dems are campaigning on ACA.
Prof 61 got 45% odd votes which is good considering Pharma spend 120M $ on negative ads & it was an insurgency campaign. None of the Dem establishment came out for it big. The Bernie wing was reeling under the loss & Sanders was everywhere, campaigning for multiple issues. Our-Revolution was not even born. 45% with little support from Dems was a good result. Next time, it possibly would win.
Change never comes in 1 day. The Tea party didn't win 1 fine day. Slowly establishment GOP embraced them. A large chunk of establishment Dems will also have to embrace the left wing ideology (Today 75% of the Dem caucus support a 15$ Min Wage as an example). Feingold didn't tun a great campaign but the DSCC pulled ads when they saw him leading big while he was up against 100M $. Clinton never campaigned for him. He won more counties than Clinton did but never had some of the high margins in core Dem counties of Clinton (those voters didn't bother & turn out to vote for him).
Progressives haven't swept the slate but I don't think they will either. It will be a gradual process & by 4 years, the Dem party will be a LOT different compared to 2016 (& it already is to a large extent). You have to judge for a longer duration.