Both arguments (that it is about Wentz and that he's not going to be a QB) make sense. You could also say they just took the BPA.
I think Murphy summed the Hurts-as-QB scenario pretty well.
For at least the next four seasons, the Eagles will pay Hurts a fraction of the going rate for a veteran backup. That could mean an extra $5 million to $10 million of salary-cap space that they can invest in another position. Plus, if Hurts reaches his ceiling, the Eagles will have a better second-string quarterback than many teams have as their starter.
Even if they have little concern about the cumulative effect of the knee, back, and head injuries that Wentz has sustained during his first four years, they might feel that Wentz’s physical style of play leaves him with an elevated risk of missing time in any given season. If you could somehow guarantee that Hurts would become a top-flight NFL backup, and you were unenthused with the other options on the board, you could easily make the case that spending a No. 53 overall pick on him is good value.
_Problem is, history offers no such guarantees. In fact, it indicates the opposite.
(He goes on to point out that only 5 of the last 21 second-round QBs amounted to anything and that's a list that include Kaepernick, Derek Carr and Drew Brees, i.e. it goes back many years.)
I feel like the Eagles winning the Super Bowl with Foles has probably made them overvalue the back-up QB. What has happened the last two years is far more normal: if you lose your starting QB, you aren't really going anywhere (never mind that last year's team wasn't anyway). If they lose Wentz this year they probably aren't making the playoffs (unless it happens very early or very late).