This seemed rather obvious to me...

Key point —> Barr and DAG Rosen never have served as prosecutors. So when they posit the Stone sentence is too high, they don’t have a well of experience to pull from based on other defendants. So instead they determine it’s too high - for a white guy like them. https://t.co/HhcAJTZkVE

— @JulieZebrak (@JulieZebrak) February 15, 2020

...but knowing they have zero experience as criminal prosecutors cinches it for me.

My lone criminal case in Federal court, my (court-appointed) client was a felon charged with possession of a firearm.  The government attorney didn't even blink at sending him back to jail, for, IIRC, the maximum sentence allowed.  I've met prosecuting attorneys socially; they have no compunction about sentencing those they prosecute.  They are mickle in their wroth and rather frighteningly sure in their self-confidence.  Prosecutors don't worry all that much about harshness.

Non-criminal lawyers may think it's a cruel system.  Then again, I don't think Barr cares one way or the other, which is the bigger problem.  He knew Trump was rumbling, he wanted to do his master's bidding.  What his actions betray is either a lack of knowledge as to how trials are conducted and how attorneys need to have stable relationships with judges to the judges know they are reliable, or a complete disregard for anyone not named "Donald Trump".  That's why so many DOJ lawyers are now worrying:

“I’m sure that some D.O.J. attorneys feel that judges are not going to look at them in the same way,” said Mary McCord, a former assistant attorney general for the department’s national security division. “And I’m sure there are judges who are going to wonder, ‘Can we credit what you say, or is D.O.J. going to come back tomorrow and say something different?’”

This happened last November, and one DOJ lawyer tried to withdraw from one of the census cases because his reputation before that judge was in danger of being shredded (through no fault of his own).  The judge wasn't having it, and it left the DOJ in a completely untenable position, again because Trump insisted his will be done.

We haven't heard the last of this.