The states where he did best in were ones with large groups of the lower educated underemployed workers or unemployed. The ones that really took the wind out of Clinton's sails were Wisconsin, Michigan, Ohio and Pennsylvania, where there are large numbers of people displaced by the changes to our economy over the past 30 years. As opposed to Colorado, CA, WA and the north eastern states. Those states have been doing OK.
From what you say, Trump won because he won crossover voters from the Democratic party. That was definitely true in WI, MI and OH, where there is also considerable economic hardship. I don't know that the blue collar manufacturing worker in those states were ever radical left. They were from a working class union tradition. That said, WI and MI voted for Sanders in the primary, so maybe I'm just hung up on the term radical left. I think Sanders was more centrist than radical left. His trade policies would have resonated better with them than Clinton's half-hearted concepts that she reluctantly adopted from Bernie. Trump's words seemed to resonate better, that's certain.
CO Democratic voters went strongly to Bernie, I assume that many of these voters are who you allude to as radical left. Bernie won Oregon by pretty good numbers. I can say for a fact that a good number of Oregon's Democratic Party voters are radical left. If what you say is true -- that left wing voters were attracted to Trump -- why then didn't Colorado or Oregon go for Trump in the national election?
What I find hard to believe is that radical left voters were drawn to Trump's rhetoric in large numbers. Partly because the radical left doesn't have large numbers and partly because Trump's racism and other nasty traits are anathema to the left.