Arizona elected not to chase LeSean McCoy. (Getty Images)

The LeSean McCoy - Kiko Alonso trade shook up the NFL landscape quite a bit. Several reporters have said the whole thing came together in about 20 minutes, but that doesn't exactly align with the comments made by Arizona Cardinals coach Bruce Arians on NFL AM on Wednesday morning.

Arians continued on to say that it was a great move for Buffalo, that Alonso is still a great player, and that Chip Kelly is doing "one heck of a job" building a culture in Philly, but the "wasn't a fit" line is what we want to dig into here. There's no telling whether Arians meant a conceptual fit in the Cardinals' blocking scheme, a salary fit or a skill fit given the other players on the roster.

To say McCoy isn't a conceptual fit scheme-wise for Arizona wouldn't make all that much sense. Chip Kelly's spread offense in Philadelphia utilizes a zone blocking scheme where the object is mostly to run the ball right up the middle (inside zone) or get to the perimeter before hitting a cutback lane to get to the second level (outside zone). Arizona similarly relies on a zone blocking scheme (though their runs are used more often to set up a downfield passing attack rather than as the foundation of the offense), so McCoy would have fit right in, in theory.

It's the salary and skill fit where Arians is on the mark. Arizona currently has just south of $14 million in cap space, according to Spotrac, which tracks the salaries of every team and player in the league. McCoy has a cap hit of $10.25 million for the 2015 season, second-highest among running backs behind only Adrian Peterson, who may or may not be cut in the days leading up to the March 10 start of free agency. The Cardinals, meanwhile, have three running backs -- Andre Ellington, Stepfan Taylor and Marion Grice -- under contract for a total of $1.756 million.

In a pure skill sense, McCoy is similar to Ellington in that they're both shifty backs who excel in open space. McCoy is obviously the better talent; he basically extrapolates Ellington's skill set to the extreme. But is it worth it to pay McCoy nearly 17 times what they're paying Ellington, in addition to whatever draft pick or player cost the Cardinals would have incurred to acquire McCoy when all those resources could instead be spent upgrading the offensive line (the fourth-worst run-blocking unit in the league last season, per Pro Football Focus) or finding a quarterback of the future?

Arians obviously didn't think so. It likely makes more sense for the Cards to look into finding a power complement for the speedy Ellington. Given the depth and strength of this year's crop of running backs, it shouldn't be that difficult to find a workable option in the draft, even in the later rounds.