Beto was on the attack plenty. If the supporters of Cruz or Trump were capable of being embarrassed into not voting we’d see that strategy employed successfully.
I know we don’t like to admit it, but Beto ran into the fact that there’s just more GOP voters than there are Dems in Texas.
Nate Silver talked about this in regards to Jaime Harrison in the 2020 South Carolina Senate race. There was a poll taken that showed Harrison down by 2 points to Lindsay Graham, 46-44 (if I recall correctly), and Silver pointed out that 44% of the voters self-identified as Democrats and that was a great showing on Harrison’s part (in other words, he had obtained the support of pretty much every South Carolina voters who would be willing to vote for him). That missing 10% wasn’t truly independent, they were Republicans who didn’t like Lindsay Graham but were still going to vote for him against Harrison when it counted.
I would be shocked if the same misunderstanding of the polling data by the media wasn’t happening here. We already know that Allred has run a shit campaign-do we really think voters are coming around to him and they’ve only recently discovered a distaste for Ted Cruz?