Currently here's what I think will happen:
1% chance of a Cruz 20+ point win
2% chance of a Cruz 15-19 point win
15% chance of a Cruz 10-14 point win
55% chance of a Cruz 5-9 point win
26% chance of a Cruz 0-4 point win
0.7% chance of a Beto 0-4 point win
0.2% chance of a Beto 5-9 point win
<0.1% chance of a Beto 10-14 point win
<0.1% chance of a Beto 15+ point win
FTFY
You do realize Cruz is only leading by 6, whereas Sherrod Brown, who you think is very vulnerable, is leading by 18?
'very vulnerable' is an exaggeration. I have Sherrod favored to win. Furthermore, I simply don't believe there are enough votes to elect a Democrat in Texas regardless of the environment.
If Alabama can send a Democrat to the Senate, then so can Texas. Don't be dense.
If Brown is leading so largely in Ohio and if Cruz is not polling so well in Texas, then that gives a good reason for the Democrats to focus more of their efforts on Texas than Ohio, which could give them hope in Texas.