From what I gathered from the plea they were assum

From what I gathered from the plea they were assuming an offense level of 10 -I previously posted supporting documentation from the federal sentencing guidelines-and the plea reduced the offense level by 2 steps for any offense level below 14  -which would've resulted in an offense level of 8 

and THEN the prosecutor was required, as per the plea deal, to ask for the lowest sentence within that offense level -which for level 8 would be probation for a 1st offense-as you can see from the federal sentencing table below

I have highlighted offense level 8 -(which as per the offense level guidelines I posted should've been the offense level and thats what Bobs lawyer was no doubt depending on in helping negotiate a plea which would reduce an offense level of 10 to a level of 8 and thus result in probation as per the next step of the plea deal), which shows a sentencing range of probation to 6 months prison for a 1st offense

So either the judge gave the max sentence for offense level 8 or he found another 4 steps of aggravating circumstances not seen by the prosecutor or me from the guidelines (very unlikely,especially with a plea) and then, as per the plea, an offense level of 12 was reduced 2 steps to level 10, which has a minimum sentence of 6 months-or he found 1 extra offense level-which would result in offense level 9 below -with a range of 4 to 10 months . I've underlined offense level 10, which has a sentencing range from 6 to 12 months for a 1st offense.

The judge didnt specify in the official published judgment that I saw how he arrived at the sentence of 6 months-and that kind of thing (not showing his math or reasoning) is what leads to appeals, though an appeal for a 6 month sentence is unlikely.

SENTENCING TABLE
(in months of imprisonment)
Criminal History Category (Criminal History Points)
Offense
Level
I -this is the 1st set of numbers in each row-which is the sentencing range for a 1st offense,the 2nd row to the right on each line is for a 2nd offense and so on
(0 or 1)
II-2nd set of numbers in each row
(2 or 3)
III-and so on
(4, 5, 6)
IV
(7, 8, 9)
V
(10, 11, 12)
VI
(13 or more)

Zone A
1 0-6 0-6 0-6 0-6 0-6 0-6 months
2 0-6 0-6 0-6 0-6 0-6 1-7
3 0-6 0-6 0-6 0-6 2-8 3-9
4 0-6 0-6 0-6 2-8 4-10 6-12
5 0-6 0-6 1-7 4-10 6-12 9-15
6 0-6 1-7 2-8 6-12 9-15 12-18
7 0-6 2-8 4-10 8-14 12-18 15-21
8 0-6 4-10 6-12 10-16 15-21 18-24

Zone B
9 4-10 6-12 8-14 12-18 18-24 21-27
10 6-12 8-14 10-16 15-21 21-27 24-30

Zone C
11 8-14 10-16 12-18 18-24 24-30 27-33
12 10-16 12-18 15-21 21-27 27-33 30-37