CHARLOTTE, N.C. -- The Carolina Panthers’ decision to trade for 33-year-old pass-rush specialist Jared Allen is a sign of three things:

• The Panthers are concerned veteran defensive end Charles Johnson will miss more than a couple of games with the hamstring injury he suffered in Sunday’s 27-22 victory over New Orleans. Johnson already has been ruled out for Sunday’s game at Tampa Bay.

• The Panthers are concerned about their lack of a pass rush in general, with only one sack each in the past two games, and that none of the ends on their roster would be able to fill that role.

• The Panthers believe that at 3-0 they are on the cusp of something special if they can get a pass-rusher such as Allen (134 career sacks) to contribute to a defense that already ranks seventh in the NFL.

Johnson missed most of training camp dealing with the right hamstring that was so badly reinjured on Sunday he had to be taken off the field in a cart. Coach Ron Rivera didn’t hesitate after the game to say how concerned he was about that.

Johnson already was coming off a 2014 season in which he had only 8.5 sacks, his lowest total since 2009. The hamstring also was an issue then, even though he didn’t miss a start.

The Carolina defense is predicated on getting a good rush with the front four. The 2013 unit that ranked No. 2 in the NFL in total defense led the league with 60 sacks. Ends Johnson and Greg Hardy combined for 26 with Hardy collecting 15.

Last season, with Hardy playing in only one game while dealing with his domestic violence issue, the Panthers had only 40 sacks. Mario Addison, Kony Ealy and Wes Horton combined for 13.5 while tag-teaming the end position opposite Johnson.

None were the threat Hardy was.

There was hope Ealy or Frank Alexander would fill the role as a full-time end this season. But Alexander suffered a season-ending Achilles injury in training camp.

And Ealy doesn’t have a sack in three games.

The Panthers signed outside linebacker Shaq Thompson in hopes that grouping him with middle linebacker Luke Kuechly and outside linebacker Thomas Davis could manufacture more quarterback pressure with blitzes.

Kuechly has missed the past two-and-a-half games with a concussion, and his status for Sunday remains uncertain despite signs he could return. Davis’ status for Tampa Bay is pending an MRI on his injured shoulder.

Kuechly, Davis and Thompson have one sack each.

Opponents have gone to a quick passing game with three- and five-step drops to negate Carolina’s pressure. That enabled New Orleans quarterback Josh McCown, replacing the injured Drew Brees, to complete 19 of his first 20 pass attempts.

The Panthers needed a spectacular game-saving interception from cornerback Josh Norman with 1:09 remaining to preserve the win.

Allen never quite fit into Chicago’s 3-4 scheme as a standup outside linebacker. As an end with the Bears in 2014, he had 5.5 sacks.

Returning to end in a more traditional 4-3 scheme could resurrect his career.

In his previous seven seasons before going to Chicago -- six with Minnesota and one with Kansas City -- he had double-digit sacks every year. Four times he had 14.5 sacks or more, including 22 in 2011.

The trade for Allen is a sign that general manager Dave Gettleman believes the Panthers have a chance to be a championship contender. He hasn’t panicked and signed big-name players the past two seasons when injuries have occurred.

The best example of that is he didn’t sign a No. 1 wide receiver to replace Kelvin Benjamin after the team’s 2014 first-round pick suffered a season-ending knee injury in training camp.

That the Panthers reportedly gave up only a future sixth-round pick for Allen and have to pay him only $830,000 makes this feel like a quick-fix solution that offered more reward than risk.

It definitely is a sign of concern about Johnson and the pass rush.