It's not profound at all and I don't think too many people, including JBB, have come to the bolded conclusion. Despite any public statements of confidence, which is part of his job whether he believes what he is saying or not, JBB knows that we're on the back side of the bell curve you mention. He believes that we're still near the top of it, but we're definitely on the back side and TJ trade or not, we were still going to be on the backside with no path back to the other side any time soon. In short, this is not a team that is building toward something, it is a team that is trying to hold on to what it is and has been for as long as it can. So what JBB did was make a choice that he thinks can help the team win now and it really didn't matter if he overpaid or not because the future is already set and future is the backside of the bell curve. You said so yourself.
As for your assertions about JBB's ability to get defensive help and how apparently easy that would have been, you don't have the first clue either as to what opportunities were available to the TB Lightning, not to other teams, and a what price.