Yes another 2020 Bernie Sanders US Presidential Campaign post-mortem.

There are three key takeaways, with a hidden fourth one (bolded)

https://jacobinmag.com/2020/04/david-sirota-bernie-sanders-2020-campaign

1. Bernie is a deeply principled lawmaker, but he is not a scorched-earth politician and never has been. Since he was first elected to a public office, his approach is one that seems defined by a belief that to make real change from the outside, you must push hard, but always maintain one foot inside the power structure and not try to burn it all the way down. The calculation is that if you are too adversarial against the establishment, you will be instantly marginalized, depicted as irrelevant and disempowered. (Side note: as the primary results show, the problem with this theory is that even if you are nice and don’t go scorched earth, the power structure has other ways to defeat progressives.)
2. As he himself said, Bernie likes and respects Biden. I personally don’t believe that affinity is justified, considering Biden’s legislative record, but I’m not going to litigate that point. It is what it is.
3. The Democratic Party has manufactured a culture that creates the conventional wisdom and perception that any efforts to contrast opponents’ records from the left in a primary is “negative” and therefore destructive.

That hidden one - that's the establishment cheating Sanders, just like they did in 2016.