That is false. The concept is "average or below average", not "as low as possible". 418 (below average) does not fulfill the concept any better than 499 (also below average) or 501 (average).If you want to super achieve concept, drop its dump stat to 1 (spatk). You get 418 BST which is well below average.
Why dont we do this? It's because it is a flawed way to view concept fulfillment. You can't say we've better achieved concept fulfillment by adjusting the stat that has no bearing on the mon. BST is a fake criteria to base the concept on and is something we've heavily talked about throughout this project.
I agree that BSR is more important, but that doesn't mean we should completely ignore BST.