LONDON – Nick Fairley stood in a back corner at the Pennyhill Park Hotel in England on Thursday morning and talked about how he felt he was finally in the best shape of his career.

At the time he admitted that yes, sometimes he wonders what might have been if he had gotten in shape earlier in his Detroit Lions career. He tried, he said, not to let it bother him.

Now, it might haunt him for a long time.

Fairley is out for a yet-to-be-determined amount of time after suffering a knee injury against Atlanta -- an injury that left Jim Caldwell “not certain” whether Fairley will be able to return this year. So depending what the Lions choose to do with the defensive tackle in the offseason, there’s a chance Fairley might have played the last snaps of his Detroit career.

Lions general manager Martin Mayhew and Caldwell were going to have a tough decision to make on Fairley even if he had been healthy the entire season and continued to play at his optimal weight.

He had been a disruptive force in the middle opposite Ndamukong Suh this season, forcing offensive lines to account for both of the first-round defensive tackles as potential game-changing players. He also had appeared to be much happier with his play, often smiling when talking about his consistency.

Even Mayhew was praising how Fairley worked to get into the shape he has and the seriousness he has approached this season with.

Now, it is a season in jeopardy and depending on his rehab and what the Lions thought of what they saw, it makes the upcoming decision of trying to re-sign him or not both tougher and easier.

The easy, obvious decision would be to part ways with Fairley if he wants a decent-sized contract. In this, his contract year, he gave them seven consecutive games of consistent, high-level play. For his career, though, he has been disruptive one game and disappeared the next. He has not played 16 games in a season, either -- another concern for a long-term deal.

But the tougher decision comes because of what Fairley could still do if he is able to stay healthy. Fairley himself said he hoped he was still in the beginning stages of a long career. The injury could actually bring the team to a prove-it, short-term deal -- especially if Suh leaves during free agency and Fairley ends up not being able to return in 2014.

If a short-term deal can’t be reached at some point, Fairley’s injury might seal Detroit’s decision to move on from the mammoth defensive tackle who has potential but has never been able to reach it.

The one caveat here could be if Fairley is able to rehab well enough to come back and continue his consistent play by the end of the season. That might be the outlet for showing that even when he isn’t able to play, he can remain in shape and can continue to be effective. That maybe he truly has learned to monitor himself when it comes to his weight and then could be worth taking a chance on.

Either way, the injury leaves the Lions -- and Lions fans -- wondering this: Is Fairley a classic case of a player who decided to show up only once money and his career were on the line, or is he a player who just finally started to understand everything and put it together for a consistent career going forward?

Mayhew and Caldwell have to weigh which one fits Fairley more and how he could fit within Detroit’s scheme in the future. And they will have a half-season of healthy work, as of now, to make that judgment.

Based on the evidence of inconsistency prior to the 2014 season, the Lions may have their answer. If they can’t get Fairley to sign a short-term deal that could be beneficial to both sides and also provide Fairley the continued motivation he had this season, it might be time to move on without him.