Jerry Jones should NOT fire Jason Garrett ... and should instead give him a fat, new contract extension -- so says Emmitt Smith, who tells TMZ Sports the Cowboys coach is great!!!
A lot of fans in Dallas seem to disagree ... JG only has 2 playoff wins in 9 seasons -- but, Emmitt is going to bat for the dude regardless.
The Cowboys legend tells us the job Garrett did bringing the Cowboys back from 3-5 to NFC East Champs this season was awesome .