"They're going to say, 'Why the hell should I give all my effort if you didn't take care of the top guy?!'"

Of course, Dak is entering the final year of his 4-year rookie deal ... and Dallas is reportedly at a standstill in negotiations for his next contract.

But, Irvin says if Jerry and the 'Boys keep playing hardball and don't get the deal done soon ... it could mean big trouble for Jason Garrett's locker room.

"If you don't pay him, let's all go home," Irvin says.

Dak's new deal is expected to be a huge one ... reports say he wants to be in the area of the $30-ish MILLION per year that Carson Wentz, Aaron Rodgers and Russell Wilson just got.

Will Jerry pay that up for a guy who's only made $2.7 million over the last three years TOTAL???