The and are off to disappointing starts, but remain playoff contenders thanks to strident defenses. The Cowboys, who are allowing only 19.2 points per game, have yet to concede more than 24 in any week. The Jags had Shabazz Napier Jersey been allowing only 14 points per contest before last week's 30-14 lo s in Kansas City. These two teams meet on Sunday at 4:25 p.m. ET on CBS. Jacksonville is a 3-point road favorite in the latest Cowboys vs. Jaguars odds, up 1.5 from the opener. The Over-Under, or total number of points Vegas thinks will be scored, has slipped from 41.5 to 40. Before you make Troy Brown Jersey any Cowboys vs. Jaguars picks, you need to see what SportsLine's Mike Tierney has to say. Tierney, one of SportsLine's most proficient NFL prognosticators, has been covering the NFL for decades and reported from seven Super Bowls.More importantly, he is riding a remarkable 15-7 hot streak on against-the-spread picks involving Dallas, and anyone who has followed his advice is up big. Now, he has scrutinized Cowboys vs. Jaguars from every po sible angle to reveal a strong point-spread pick that he's sharing only over at SportsLine.Tierney knows Jaguars quarterback threw 61 pa ses last Sunday in Kansas City Ish Smith Jersey . While he racked up an impre sive 430 yards, he completed just 54 percent of his attempts and was picked off four times in the resounding defeat. For the season, he's thrown for over 1,500 yards, but only eight scores against seven interceptions. With no (hamstring), Jacksonville will again turn to T.J. Yeldon to lead the ground attack. He's netting 4.4 yards and has collected four touchdowns -- three receiving.Just because the Jaguars have been inconsistent defensively doesn't mean they can't cover on Sunday.Cowboys third-year quarterback hasn't hit the 1,000-yard mark yet this season, averaging just 172 yards per game. He's also not running as much -- only 24 yards per contest -- which is allowing defenses to drop back into coverage on obvious pa sing Anzejs Pasecniks Jersey downs. It's also made life tough on running back , who has just two rushing touchdowns this season and averaged a season-low 2.7 yards per carry last week. In last Sunday's game versus Houston, Prescott struggled to find open receivers, completing 18-of-29 pa ses for 208 yards. The also mixed secondary schemes, forcing him into two interceptions. Prescott will face similar Dwight Howard Jersey difficulties against Jacksonville's front seven that effectively camouflages blitz packages.Tierney has evaluated all of these circumstances and while we can tell you he's leaning Over, has found a crucial X-factor that determines which side of the spread you should be all over. He's sharing what it is, and who to back, only at SportsLine.So which side of the Jaguars vs. Cowboys spread should you back? And which crucial X-factor makes one side of the spread hit hard? , and find out.