The Giants SHOULDN'T bench Eli Manning -- they should block for his ass -- 'cause he's still a great QB ... so says the guy who won 2 Super Bowls with the embattled star.
TMZ Sports talked to Brandon Jacobs -- Eli's NYG teammate from 2005-2011 -- about the 1-5 Giants' crappy offense ... and whether it's time to put Manning on the pine.
"I still think right now, I think Eli is great."
B.J. says Eli's gotta be used right, 'cause he ain't the guy to operate a run-and-gun style offense.
"Eli's a pocket passer. He's a pocket passer. He'll sit there and get balls off and put balls in small areas. I've seen him do that."
It's true ... Jacobs was on the field for a bunch of huge moments -- including David Tyree's "Helmet Catch."
But, if Manning's still got it ... why do the Giants have the worst record in football?
Most of that blame falls on the NYG struggling O-line.
"I wouldn't trust the guys in front of me if I was him," Jacobs says ... "Ya ask me, the poor guy's shell-shocked."
Block for the man.