This shouldn't come as a surprise, we knew the '15 manifold was capable of flowing more air than the boss. The '11-'14 Manifold wasn't "worse" per se than the Boss 302 IM. It's more of a sidegrade piece you're trading torque for an extended rev range. The CJ however is the best of both worlds, I can assure you the CJ Mani on a '15 is going to DO work with the better exhaust cam and better heads. Stay tuned for that! it's only a matter of time my friend.
Bama is also not very good at tuning the Boss IM, and it depends on what they were willing to shift it at. The 2011-14 stock manifold has more volume than the Boss manifold too. It's power delivery is in a different part of the curve because of this. It's been proven multiple times that if you're not willing or able to shift very close to 8000, the Boss IM will lose time versus the stock 2011-14 manifold too.
Kcsvt said it best. I'll add that it's meant to do different things. Always has been. Depending on application, it wasn't always the best piece for 11-14 either.