FTR, Bray was a head case at UT so he's not the "ideal" model... just recent enough playing behind a weak OL as a Fr to make a comparison with what JG had this year.
Untrue about Bray and the OL.
Bray:
2011 - 20 ppg - not prolific
Nope. In games that Bray played, UT scored 28 ppg... including when he played injured and supposedly with the flu vs UK.
2012 - 36 ppg - prolific...but also behind the best OL since peak Fulmer days. They were 3rd nationally giving up 8 sacks. 6th nationally in TFLs allowed. 44th in rush average, similar to 2015, yet without an nfl back on the roster.
Well... yeah. Bray knew how to see coverage, make good reads, and get the ball out in a hurry when he had to. That makes the OL look better.
I don't think anyone is saying that the '18 OL was a great one. But it didn't help that JG doesn't know how to do what Bray and others have done very well.
Interesting that you seemed to have avoided the best year to prove my point. In his Fr year, Bray didn't play much until UGA and didn't start until two games later. An OL that supposedly couldn't pass block suddenly got much better. An O that only went over 20 pts vs one FBS opponent (UAB) in the first 7 attempts... averaged 35 ppg behind Bray who though cursed with feet of stone... knew how and when to get the ball out.
You don't even have to look that far back. JG fans LOVE to trash Dormady... but in the 3 games where only he played with the starters UT averaged 35 ppg. Only 17 when they split time vs UMass... then the UGA disaster. In 5 games, QD only took a sack 3 times. JG was sacked 32 times. Yes. JG had a better completion % but the O would have been better if he'd thrown the ball away more.
I don't even understand your statement on taking JG as a 55% passer and winning more games, makes no sense. You're really saying you'd accept a worse qb if the TEAM won more. The only way that could happen is if run and defense improved. Nothing to do with jg.
That's not really surprising.
But here is at least one more way that a QB could be more effective with a lower completion %. Opposing D's often gave JG short check downs on 3rd down. He took them... and the drive ended. If he had thrown something downfield on each of those failed conversions and completed 40% for a first down then UT would have sustained more drives and likely scored more points with him having a lower completion %. If he threw more down the middle of the field... more slants... more plays where he led receivers into YAC... those plays would have brought his completion % down but could have helped the O be more effective.
UT was 10th in the SEC in 3rd down conversions and 11th in pass plays over 10 yards. Oddly... the Vols were better comparatively at passes over 20 yards primarily because of the jump ball types of passes he threw vs Auburn and UK. What that basically boils down to is the fact that completion % does not always equate to effective offensive drives or points.