That's a big part of it. They've had a chance to have their top developmental guys (as well as AA) get an extended look at Contreras, Pache, Waters, Shewmake, Langeliers, Davidson, De La Cruz, and Muller - which is something that doesn't take place in a typical minor league season. AA and his most trusted lieutenants don't get to make multiple trips to Mississippi, Florida, and Rome to stay and watch these guys for a week or two at a time. They've gotten to see these kids compete, go through stretches when things are going good and bad, and have been able to get a much better feel for them since they've been able to watch them all summer. There's always going to be at least some doubt when you see them in a typical season - did you catch them when they were going good? Right after they broke up with a girlfriend? Whatever.
The younger guys have gotten to play against significantly more advanced competition than they would have playing in A ball (or even AA) simply because they were drafted recently. The organization has never shown any reluctance to push players aggressively until they show that they need to slow them down, and it doesn't look like that's going to change under AA. The longer look they've gotten this summer gives them a much better feel for whether or not some of these guys are legitimate everyday players, and if so it makes sense to take more time with them. The reports about Shewmake have been all over the place since well before he was drafted - questionable defense/too big and lumbering/etc.. The decision makers have had a chance to see those questions answered this year against top-tier prospects and young players with MLB experience rather than guys at the appropriate level because of their age. You can tell a LOT more about our young hitters when they're hitting against Wilson/Touki/Newk/Folty than you can when they're hitting against your average AA and AAA pitchers who have little chance of becoming MLB SPs.
It's unfortunate that WE don't get to see or hear about what's going on at Gwinnett, but AA and his guys have likely gotten a MUCH better feel for the players at the alternate site than they ever would have if this had been a "normal" summer.