The decision, combined with the choice to promote Michael Vick to franchise quarterback, will define the post-McNabb portion of Reid's tenure here.
Each bit Reid last year: Vick, by leading a turnover-prone offense; Castillo, by losing five fourth-quarter leads. Vick was coming back no matter what. But in Castillo, Reid has now made not just one audacious bet, he has doubled down, even when he had a chance to change course.
In the end, months of fevered speculation about Reid's choice ended in an anticlimactic text message that simply announced the hiring of new secondary coach Todd Bowles and a Reid news conference at noon on Tuesday.
Just about status quo.
Normally, that wouldn't make for a big headline. But the move and the reaction to it are less about the particulars and more about Reid, whose every decision splits Eagles fans into a hardened camps reminiscent of the red state-blue state divide.
Depending on your perspective, Reid is either showing the kind of patience that has marked his mostly successful run in Philadelphia and Castillo is bound to improve, or the head coach is displaying the stubbornness that has delivered three seasons without a playoff win.
More will be heard from Reid Tuesday, and no doubt he will assure listeners that Castillo was his first choice all along, despite more than one report that the Eagles were in the Steve Spagnuolo sweepstakes.
Reid will surely point to his defense's four-game improvement at the end of the season, when the Eagles surged to a final ranking of 10th in points allowed.
But those games had little meaning and little pressure, thanks in large part to a defense that ranked 22d in points after the first 12 games, the ones in which the Eagles had a realistic shot at the postseason. Their late rally reflected improvement, but against poor quarterbacks.
Putting too much emphasis on final numbers ignores what was seen in the critical moments that alter the course of a season.
