A Cowboys legend is weighing in on the QB controversy in Dallas -- with Jay Novacek telling TMZ Sports ... KEEP DAK PRESCOTT UNDER CENTER ... even when Tony Romo returns.
Jay -- a 5-time Pro Bowler, 3-time Super Bowl champ with the Cowboys -- says he's a big Romo fan and wants to see him play again ... but essentially says the team has a great thing going with Dak!
"When Tony's ready to play, I'd sure enough start Dak ... and just always have that little back up situation going there," Jay said.