J.J. McCarthy has been through a roller coaster ride this season with the Minnesota Vikings. On Sunday, he helped his team to a 34-26 victory over the Dallas Cowboys. In this game, McCarthy, who's been inconsistent on the field, completed 15 of 24 passes for 250 yards and three total touchdowns.However, retired Hall of Famer Cris Carter still criticized the quarterback for his antics during this Week 15 game. On Sunday, on the "Up & Adams" show, they shared their thoughts on J.J. McCarthy's rushing touchdown in the second quarter when he did the griddy into the end zone.Carter said that the quarterback showed immaturity with the way he behaved on the field. He believes that McCarthy still has a long road of mental development and maturity."To me, that's not what KOC (Kevin O' Connell) wants from his quarterback," Carter said. "Like that alternate personality, number nine, all that stuff. No one's ever won in the NFL doing this. So, you know, to me, he acts like a kid, he's played like a kid, we're stuck with a kid until next year."After missing his entire rookie campaign due to a season-ending injury, J.J. McCarthy returned as the QB1 this season. However, he suffered a high ankle sprain in Week 2 against the Falcons. This sidelined him until Week 9 when he led them to a 27-24 victory over the Lions.Following that victory, the Vikings went on a four-game losing streak. J.J. McCarthy was benched during the loss to the Seahawks in Week 13 due to a concussion. So far in eight games, he has tallied 1,342 yards and 11 TDs passing, along with three rushing touchdowns and 11 interceptions to his name.Rex Ryan downplays J.J. McCarthy's peformance while heavily criticizing the Cowboys' defense in Week 15Ex-NFL coach turned analyst Rex Ryan blamed the Cowboys' defense for their disappointing loss to the Vikings.During Monday's episode of ESPN's "Get Up," he highlighted the mistakes made by Brian Schottenheimer's defense, which has been ranked fourth from last (No.29) this season."Defense," Ryan said. "I mean, 100% this is Super Bowl caliber offense. We've seen it all year. But this defense stinks. They made J.J. McCarthy look like Frank Tarkenton, and he's been on the struggle bus all season. ...They absolutely stink. I've called them dumb state defense all season long. And guess what? The dumb state defense is going to keep your team parked there for the playoffs, because no way in hell you're getting there."As per reports, the Cowboys now have a 1% chance of making the playoffs.On the other hand, the Vikings are placed last in the NFC North with a 6-8 record. They next face the Giants on Sunday at 1 p.m. ET.