It might be a bit premature to say that Duke Johnson has hit the freshman wall.

But following a sensational start to his collegiate career, the University of Miami’s talented first-year tailback has definitely slowed down.

Through four games, Johnson led the nation in all-purpose yards with 838, torturing opponents any way he touched the ball. It’s been a different story the past two weeks.

In a 44-37 victory over North Carolina State on Sept. 29, Johnson was held to a season-low 82 all-purpose yards. Johnson barely improved on that last week in UM’s 41-3 loss to Notre Dame, picking up 90 yards, including only 22 yards on eight rushing attempts.

In two weeks he’s dropped from No. 1 in all purpose yards to No. 14 with an average of 168.3 yards a game.

“He’s still ultra-productive,” coach Al Golden said.

Just not as productive as he was earlier when Johnson seemed a threat to break a big play any time he ran, caught or returned the ball for the Hurricanes.

Johnson made a spectacular debut during UM’s season-opening victory against Boston College, ripping off touchdown runs of 54 and 56 yards and also had a big performance in the Hurricanes’ home-opening win against Bethune-Cookman, scoring touchdowns on a 95-yard kickoff return, a 1-yard run and a 50-yard pass from quarterback Stephen Morris.

But since piling up 200 all-purpose yards (72 rushing, 38 receiving, 90 kickoff returns) in UM’s 42-36 overtime victory against Georgia Tech on Sept. 22, Johnson has made little noise.

In his last two games, Johnson rushed 20 times but had only one carry beyond 10 yards. Aside from a 26-yard reception last week, he caught five passes for 33 yards. And he returned three combined kickoffs against N.C. State and Notre Dame, none longer than 19 yards.

Johnson was not made available for an interview this week, but teammates say the freshman is showing no signs of frustration.

“He’s the kind of kid who just shrugs things off,” sophomore receiver Phillip Dorsett said. “Obviously, teams are going to key on him because of the games he had. You can’t have a great game every week.”

Keying on Johnson was certainly the defensive game plan for North Carolina State, which stacked eight players near the line of scrimmage to slow down UM’s running game. As far as that went, the strategy worked. Johnson gained 39 yards on 12 carries and UM was held to 85 yards on 32 attempts.

But the plan backfired when the Hurricanes abandoned the running game and burned the Wolfpack for a record 566 yards passing in the 44-37 win.

Nothing worked for Miami’s offense and Johnson last week against Notre Dame. His long run was for 7 yards and he gained only 4 yards on three carries during two unproductive series in the third quarter that helped turn the game around.

The Irish held UM (4-2, 3-0 ACC) to 285 yards and allowed the Hurricanes to run off just 53 plays. The week before against N.C. State, Miami snapped the ball 88 times.

“When you get more plays, you get more opportunities to … get the ball in Duke’s hands,” offensive coordinator Jedd Fisch said. “Our ratio of plays run and touches he had was good. We didn’t have enough because we didn’t run enough plays.”

Johnson and the Hurricanes face North Carolina (4-2, 1-1 ACC) on Saturday at Sun Life Stadium. The Tar Heels feature a defense that is ranked 11th nationally against the run, allowing 86.3 yards per game.

But Carolina’s best defense against Johnson may be a good offense. The Hurricanes defenders have been giving up points and yards at a historic pace and spent nearly 40 minutes of last week’s game against Notre Dame on the field.

Johnson can’t be very productive if he’s sitting on the bench.

“There’s a lot of plays designed for [Johnson] or Phillip {Dorsett] or whoever are the playmakers, but when you get behind and [opponents are] running the ball effectively, it’s hard to stay on schedule with what you want to do,” Golden said. “We’d like to see [Johnson] be more impactful and one way to do that is to make sure we’re playing good with all three units.”