The Cowboys need a better plan at backup QB, but that plan may not necessarily involve a first-round pick.
In the NFL these days, there's an expectation that a QB drafted in the first round needs to be an immediate starter, and the numbers seem to bear this out. Of the 12 quarterbacks drafted with a Top 40 pick in the last four drafts, all but one were immediate starters for their teams in their rookie seasons.
The only exception was Johnny Manziel, who was certainly expected to be an immediate starter in Cleveland, but failed to do so for a number of reasons.