Yeah the "Warren took thousands of progressive votes from Bernie" thing not only doesn't pan out considering Warren's own numbers (some of which would have gone to Biden, not Bernie), but also when you consider that Bloomberg took thousands of centrist votes from Biden, and actually out-performed Warren in many Biden-winning states.
Just for one example, Bloomberg's poorest showing was 8% in Minnesota, that "contested liberal state" - but Biden+Bloomberg still beats Sanders+Warren there. In fact, if we do that across the board - give all Bloomberg's votes to Biden, in addition to giving all Warren's votes to Sanders - it looks like you only meaningfully flip a single state, Massachusetts. Maine is still considered too close to call right now, but in the best case while it does switch from a very narrow Biden victory to a very narrow Sanders victory, this "gain" disappears because Biden would take more delegates away from Sanders in California and Texas than Bernie gains by flipping Maine. So nah, it doesn't work out. Biden didn't win all these states because the progressive vote was split, he won because he is genuinely more popular with the base in those states.