They were once teammates. They are now sworn enemies.
Daymond Langkow has been one of Calgary's best centers for several seasons now, but missed almost all of the 2010-11 season with a fractured vertebrae. Even before the injury, Calgary coaches didn't have Langkow next to Jarome Iginla on a consistent basis, which meant he saw a wide variety of match-ups (opposing coaches tend to focus on Jarome). In 2009-10, he had the most difficult zone-start ratio of any regular Flames' forward, but that was the first year he took on such a difficult assignment. Further, his offense has steadily declined as he's gotten older going from 0.95 points per game in 2006-07 when he was thirty years old, to 0.81 at 31, 0.67 at 32, 0.51 at 33, which was followed by the aforementioned season in the E.R. His possession numbers were strong all down the line, but the $4.5M cap hit, the decline in offense, and the serious injury all suggest to me that if you have the depth to take the hit, it may indeed be a wise time to divest.
The Flames have the depth - or at least, they do when everyone is healthy. Brendan Morrison, Matt Stajan, Olli Jokinen, and Mikael Backlund are all capable NHL centers, and in fact, are the group of centers that Calgary used most of last season. Each one is cheaper, and each comes without the ominous cloud of serious injury hanging overhead, and while not one of these men was able to do the job at even strength that Langkow did in 2009-10, the Flames as a team were actually one of the better clubs in terms of possession.
Where the team had a little bit less to work with was on the wings, which is where the acquisition of Lee Stemniak comes in. Stempniak is on the last year of a deal that will pay him $2.3M in cash at a cap hit of $1.9M, which means that the Flames are saving $2.2M in cash and $2.6M against the cap with this deal. And while Stempniak may not have the same potential payoff this season as Langkow (should he prove healthy and effective), he's a player who's in the prime of his career, and has been able to produce pretty good offense at even strength with at least fifteen even strength goals and thirty even strength points in each of the last two seasons. If he's afforded power play time (unlikely), a fifty-point season isn't out of the question. That he's in his contract year and not making too much also makes him a much more liquid asset than Langkow (who had a no-movement clause) should the Flames decide to move him at the deadline for a draft pick or prospect.
In the end, it's a deal that reduces risk, provides flexibility, and shores up a position of relative weakness from a position of relative strength. It may end up looking bad if Langkow has an excellent season, but I think this is a good deal for Jay Feaster and the Flames.