there were definitely a few issues
republican talking points ranged from a valid criticism of moderators to deflection, castro was middling on what stance he wanted to take regarding whether or not he wanted to paint himself as pro open borders
he'd get grilled on that angle definitely by republicans in any debate, it isn't something he can refuse to answer in any debate against trump, biden at least briefly seemed coherent enough to make a cogent stance on it
Castro waffling is I think, his realization that he has a better shot than Beto does at winning the Dem Primary for Senate and knocking off John Cornyn just on name ID. (He sort of has it, Cornyn needs to spend millions of dollars again just to make people aware that he exists despite being the sitting senator) and so not wanting to commit to anything. Which ironically, (or not ironically) is what he slammed O'Rouke on.
Going on my tangent a bit more.
Delaney also wasn't entirely off the mark, it is easy to promise the moon but can you deliver. Pragmatism/feasibility isn't incompatible with big ideas.
Like for healthcare, dollars for result wise the States is awful, picking the broken system angle is better than getting whittled into a hard corner about needing to come up with trillions to throw into said system.
As well, you need presentable solutions as opposed to abstract goals.
For example, one candidate to tackle greening, his ideas were along the lines of reinventing the coal and middle areas from fossil fuels to solar industry and panel production. This was good on multiple fronts
as it actually specifies a strategy (solar, built in the States), it acknowledges grievances (loss of jobs from coal), and offers a fix (transitioning the coal area to green jobs).
Simply leaving it at vague renewable energy and only homing on killing coal with no alternative just justifies a group to side against you.
