Casspi is a better player than Barnes. Period. He was better last year, and he's been better this year once again. He should be getting Barnes' minutes, and Barnes should be getting DNP-CDs. There's really no argument for Barnes at this point.
His advanced impact stats have been better both years:
2015-16
RAPM:
Casspi = +1.39
Barnes = -3.40
ORAPM:
Casspi = +1.07
Barnes = -1.58
DRAPM:
Casspi = +0.32
Barnes: = -1.81
RPM:
Casspi = +0.96
Barnes = -1.39
ORPM:
Casspi = +0.34
Barnes = -0.45
DRPM:
Casspi = +0.62
Barnes = -1.39
Net On/Off:
Casspi = +6.1
Barnes = -5.4
Off On/Off:
Casspi = +3.1
Barnes = -1.5
Def On/Off:
Casspi = -2.9
Barnes = +3.9
Literally, every single one of those impact stats in 2015-16 (whether it's offensive or defensive) favors Casspi. Now let's look at the 2016-17 season.
2016-17
RPM:
Casspi = -1.70
Barnes = -2.42
ORPM:
Casspi = -1.81
Barnes = -1.15
DRPM:
Casspi = +0.11
Barnes = -1.27
Net On/Off:
Casspi = +2.3
Barnes = -6.1
Off On/Off:
Casspi = -0.9
Barnes = -1.3
Def On/Off:
Casspi = -3.2
Barnes = +4.9
The only thing that favors Barnes here is ORPM. However, overall RPM is in favor of Casspi. Still nothing here suggesting that Barnes should be playing over Casspi.
What about just some simple stats over the last 2 years?
2015-16
Casspi (per100): .587 TS% / .481 FG% / .409 3PT% / .648 FT% / 20.8 PPG / 10.5 RPG / 2.4 APG / 1.4 SPG / 0.4 BPG / 2.4 TOPG / 3.9 FPG
Barnes (per100): .503 TS% / .381 FG% / .322 3PT% / .804 FT% / 17.8 PPG / 9.9 RPG / 3.8 APG / 1.8 SPG / 1.3 BPG / 2.8 TOPG / 5.5 FPG
2016-17
Casspi (per100): .510 TS% / .451 FG% / .379 3PT% / .588 FT% / 16.8 PPG / 10.8 RPG / 3.4 APG / 1.2 SPG / 0.1 BPG / 2.3 TOPG / 2.9 FPG
Barnes (per100): .491 TS% / .374 FG% / .328 3PT% / .681 FT% / 14.6 PPG / 9.4 RPG / 5.6 APG / 1.4 SPG / 0.7 BPG / 3.2 TOPG / 4.6 FPG
So Casspi is a better & more efficient scorer, better shooter, better rebounder, less turnover prone, and less foul prone while Barnes is a better free throw shooter, passer, & generates more steals & blocks. Despite Barnes having better steal & block numbers, advanced impact stats still show that Casspi helps his team defensively way more than Barnes does whether it's DRAPM, DRPM, or Defensive On/Off.
What about measurements? How do they compare in size?
Height Without Shoes:
Casspi = 6' 7.75"
Barnes = 6' 6.75"
Winspan:
Casspi = 6' 9.25"
Barnes = 6' 9"
Standing Reach:
Casspi = 8' 10.5"
Barnes = 8' 0.5" (Yikes!!!)
Weight:
Casspi = 225 lbs
Barnes = 225 lbs
So Joerger is benching someone who is taller, longer, a better scorer, a more efficient scorer, a better shooter, a better rebounder, a better defender, less turnover prone, & less foul prone over Barnes. Riddle me that?