I agree. Think you are dead-on here. Without at least that, Wellman has no choice but to make a change...no matter what he wants to do. And I think he understands that.
However, if you accept that this is really only his 2nd year with his players having most of the minutes....what, 7 sophs on this team?....and he ends up with 20+ wins and a post-season appearance, I don't see how anyone can just flatly rule out that he could not accomplish even more with those guys as juniors & seniors. Anyone who cannot see major improvement this year....not just improvement, but major improvement...is simply not looking at the situation objectively.
Maybe this team will flop down the stretch, winning only 3 or 4 more games....in which case the next move by Wellman will be obvious. However, if this team continues to make strides and wins 20+ games & a post-season invite, a fair-minded person has to give [Redacted] a lot of credit for it.