Allen Park — You see it in nostalgic bursts, a leaping catch here, a sliding catch there. When everything is right — the protection, the throw, the coverage — Calvin Johnson can still be Megatron.

But the toll is mounting, and so is the cost. And when this season mercifully ends and a new regime takes over, it will face one extremely delicate question. The primary debate isn't about Matthew Stafford, no matter how loudly we shout that it is. He'll likely be back, partly because he has untapped talent and partly because the NFL has a critical quarterback shortage.

The toughest debate will be about Johnson, who said Thursday it'd be "lovely" to finish his career as a Lion. And it would be, for the fans and the franchise. The problem is, it might not be logical. It probably won't make fiscal sense for the new management group, which theoretically would be less emotionally attached to a beloved star. And it might not make sense for Johnson to stay — through another rebuild, another offensive overhaul, possibly another year of frustration.

He's 30 and in his ninth season, when many skilled players decline. Johnson is showing the effects of age and injury, although with Stafford's inconsistencies and the Lions' horrid offensive line, it's difficult to measure. In the loss to the Rams last week, Johnson caught one pass, a 16-yarder late in the game. That kept his streak alive, with at least one reception in every NFL game he's played, 132 in all.

Johnson can still be dynamic, and with 71 receptions for 981 yards, he's closing in on his sixth straight 1,000-yard season. But his per-catch average of 13.8 is a career low, a reflection of his reduced impact as a deep threat.

For all his staggering numbers, the most notable now is his $24 million hit on the 2016 salary cap. It's a mammoth figure he received at the peak of his career, and it no longer matches his production. The easiest scenario would be for Johnson to restructure the final four years on the contract, lessening the fiscal pain for the Lions. That might end up being the solution, but both sides would have to want it.

The dilemma is, the Lions could save $11 million on next year's cap by trading or releasing Johnson. With the size of the contract, a trade is problematic. With the size of the name, an outright release is dangerous.

"I'll think about it more when the time comes," Johnson said Thursday. "If that time comes, whatever happens happens, but not now."

Open questions

That's Classic Calvin, understated, polite, pleasantly evasive. He's far from done as a productive player, evidenced by his three-touchdown performance against the Eagles on Thanksgiving. But the days of domination appear over. He has battled an assortment of injuries the past few years and has one 100-yard game this season. Of his seven touchdowns, the longest is 25 yards.

Is that because the line gives Stafford little time to let deeper routes develop? Is it because Johnson no longer consistently beats physical cornerbacks? Is it because defenses still treat Megatron like Megatron, with exotic double coverages? Is it because Stafford isn't accurate enough?

The answer might be yes to all of them but it doesn't matter, because it doesn't change the financial truth. And that's why Johnson is deflecting questions about his future, while trying to deal with the present. The offense stirred a bit after Jim Bob Cooter replaced Joe Lombardi as the coordinator, but outside of the 45-14 explosion against the Eagles, it hasn't stayed lit.

"I'm not going to say I've found it harder to get open — there's times when I'm open," Johnson said. "So we just have to try to make those things happen, but oftentimes, you never know what Matt's (Stafford) read is. … When you catch the ball, you can get into the flow of the game. And not doing so, you kind of feel like you're maybe just lost in the game plan sometimes."

Against the fierce Rams pass rush, the plan was to fire quick passes, which got Golden Tate and Theo Riddick involved. But just like a unique Lions superstar from another era — Barry Sanders — it's not so easy to get Johnson involved when defenses are geared to stop him.

Looking elsewhere

Lions receiver Lance Moore, who played nine years in New Orleans and last season in Pittsburgh, said he sees defenses react to Johnson the same way they do to Steelers star Antonio Brown. Jim Caldwell has seen it all, and encounters different strategies every week.

"I think you probably didn't see as much creative coverage (in the past) as you see now," Caldwell said. "A couple weeks ago, a couple teams said, 'Hey, you know we can play him one-on-one.' And several touchdowns and big plays later, it was a little bit different."

That's been the issue since Johnson practically reinvented the position with 122 catches for 1,964 yards in 2012. His reputation still precedes him, even if the numbers aren't the same.

Some of it is simply about protection, in multiple senses. Stafford doesn't get sufficient protection, which affects the passing game. And maybe, as Johnson slows, the offense protects him by utilizing others.

"He's still extremely talented, he's a great player, there's no question about that," Stafford said. "But we have a lot of good players, and if teams want to really focus on Calvin, we have to try and make them pay with other guys."

The Lions used to make defenses pay by throwing to the best receiver of his era. It didn't pay off in playoff victories, but it paid well. Unfortunately, interest on the investment is about to come due.