After some time to reflect on the situation I can understand why Mr Allen may have felt a need for a change.
First let's look KP.
Great talent evaluator yes
Great draft resume yes
great culture yes
Good all around GM Yes
Just to name a few things
so why would Mr Allen turn so abruptly on someone
did he over value the team players, Probably
did he nix a deal at the trade deadline that Mr Allen thought would make the team better, Maybe
But I think Mr Allen felt betrayed by KP in some way and here's my theory
In Big Business when you let someone in your inner circle you are expected to protect the business interests and in the case of Tom Penn when the quote "offer" for the GM position from Minnesota was put out there did KP do his part to validate or verify the information that lead to his friend Tom's promotion and raise? I don't know but if not and Mr Allen found out there was no real offer Mr. Allen probably felt dooped and betrayed so he fires Tom and hangs KP out for all to see knowing that it's to late to fire KP and hire a new GM before the draft so he leaves KP to finish his job knowing full well once the draft is complete He's history.
some more Interesting facts
KP's house goes up for sale.
team hires firm to search for new GM.
KP says he's fighting for his job and may the best man win having a good idea his time is done.
KP gets told the draft is his last day yet works the draft?
KP comes out smelling like a rose
Mr Allen's A terrible owner.
KP's letter to fans Don't think poorly of Mr Allen he's only trying to make the team better.
Nothing Basketball related makes sense in the firing of KP only the supposed betrayal of KP in the Tom Penn negotiations seems to make sense here. take it for what it's worth