Things to remember: It's one poll, polls ~ a week and a half ago showed Cruz up ~3-4 points (interstingly, Rasmussen which typically leans R had Cruz up just 3). All 3 surveyed likely voters (and...
The margin of error was plus-or-minus 4.1 percentage points.
The MOE applies to both figures, so Cruz is at 54+/-4.1 & Beto is 45+/- 4.1, so anywhere from Cruz - 59, Beto 41 to Cruz - 51, Beto - 49 are within the margin or error.
Things to remember:
And a new Reuters poll out this morning has O'Rourke up by two points.
I really like the fivethirtyeight summaries of these races.