And when you have Donovan McNabb for 11 years, that isn't always easy.
So, navigating the course between incumbent starter Michael Vick, who has been either injured or inaccurate since 2010, and impressive rookie Nick Foles will be simple work for Reid. It should be, because rookie quarterbacks are easy meat for NFL defenses once the real games start and the other guys start disguising their coverages and blitzing. Making a case to stay with a veteran, especially one as gifted as Vick, is no problem - right now.
"I thought he did a nice job," Reid said Friday night about Foles. "I thought he managed the game well."
That tone walked the narrow line between being too effusive and too dismissive toward the 6-foot-6 Foles, who was a steady 12 for 19 for 146 yards and two touchdowns. He also threw another rookie interception, forcing a deep pass into double coverage - as he did earlier in the week against New England - but overall it was his third straight positive showing.
This one, unlike the others, came against the starting unit of the opponent and, even in the vanilla of the preseason, that means something. (It might mean the Cleveland Browns are going to stink on ice this year, but nevertheless.)
In three games, Foles is 36 for 57 for 507 yards, with six touchdowns and two interceptions. He has completed a pass play that gained at least 40 yards in each of the games. Foles has been poised, slightly more mobile than advertised, and is able to deliver a deep ball as well as complete a short pass that requires touch. He's good.
All of that is interesting and none of it is meaningful if Vick plays well this season, leaving his injury issues aside. If Vick is completely healed and healthy and he plays poorly, replicating the turnover-laden start to 2011, then Andy Reid is going to finally hit the iceberg.
For the moment, it doesn't matter if Reid pretends that the actual backup to Vick is Mike Kafka or Trent Edwards or Madman Muntz. If the offensive season needs real saving, the only guy on the roster with the tools to do it is Foles. That's a perilous spot in which to place a rookie, and it might not work, but Kafka isn't going to take the platoon over the ridge, either.
Should that scenario play out, and it is far from unlikely, it will be fascinating to see how Reid handles it. He protected and deflected for McNabb for so long that it became second nature. Most of the time, of course, he was right. McNabb was his best option.
A.J. Feeley won four of five starts with McNabb out in 2002, but was replaced in the playoffs and then didn't get a single snap in 2003. McNabb and the Eagles were still on the rise then, however, and there wasn't much outcry for Feeley.
The biggest challenge to McNabb's standing came when Jeff Garcia took over and won five straight games to end the 2006 season, won a playoff game, and then lost by three points to the Saints in the divisional round. Reid solved that budding controversy by not offering Garcia a contract for 2007.
Feeley got another minor shot in 2007, but wasn't very good, and then Kevin Kolb became the backup in 2008, joined by Wildcat specialist Vick in 2009. Once McNabb was traded, there wasn't any expectation of a Kolb-Vick controversy. Kolb was solid, if unexciting, and Vick had been terrible in 2009. No one could have anticipated the season-opening concussion to Kolb that made possible Vick's MVP-caliber 2010 season.
That put Vick solidly in the starter's role, and when he faltered last season there wasn't any particular clamor to see more snaps for Vince Young. This current situation is unique, and unique in Reid's coaching career, because it is legitimate and it is blossoming just as the season is set to begin.
Beyond the statistics Foles has amassed - which are nice, but Edwards had good stats on Friday, too - what is impressive is his coolness under fire. There was a play on Friday night when a pass rusher fought off a block and fell at the quarterback's feet as Foles stood in the pocket and looked downfield. Rookies, and some veterans, will often react to that as if a rattlesnake has been thrown on the ground near them. Foles didn't even glance down. He just kicked at the guy a little with his back foot and then delivered the pass.
Picking up the blitz, looking off defenders, making the right reads, all of that can be coached. Standing in the pocket when there are snakes on the ground, that can't be coached. Coming back confidently after throwing an interception, that can't be coached.
"You're looking at that as a coach - does he get gun-shy or does he continue to fire?" Reid said. "He did it. He stayed aggressive and did a pretty nice job, I thought."
Reid sees what the rest of us do, and he knows where this can lead. There is always a segment of fans that want to try the big, strong kid whose main selling point is that he hasn't failed yet. There is always a segment of fans, for various reasons, that would be happy to see Michael Vick replaced. Those two constituencies could come together very quickly in a few weeks.
They might not form a critical mass. Reid won't care what the fans think. But in this most tenuous of seasons, it will be the most critical and crucial decision he has ever faced.
Contact Bob Ford at email@example.com, or follow on Twitter @bobfordsports. Read his blog, "Post Patterns," at www.philly.com/postpatterns