New York Giants legend Amani Toomer tells TMZ Sports the problem in NY ain't Eli Manning ... it's his trash O-line!!!
Of course ... Amani's biased -- dude is rockin' a Super Bowl ring these days 'cause of Eli's heroics in SB XLII -- but he swears he's tellin' the truth.
"I'm not an Eli apologist," Toomer tells us ... "I just think that, in my honest opinion, I just don't think Eli's it -- I don't think he's the issue."
So, what is? Amani tells us look at the five dudes in front of Manning for that.