The good news is that in the 4-3 defense, the linebackers don't have to be all-stars so long as the defensive line is solid. The bad news is that the Cardinals' defensive line is decidedly not solid.
James Darling anchors the middle. A ten year veteran, he would easily be referred to as "pops" in a linebacking corps that averages less than 4 years of NFL experience. While he was productive in his own way in 2005 (87 tackles, 2 INTs), he's definitely not a long-term solution at the position and hopefully will suffice as a stopgap until a younger player from the squad can fill his shoes.
Karlos Dansby patrols the strong side. After three years in the league, he has yet to establish himself as a rising star (much like every other linebacker on the roster) but he's definitely not the weakest link. And that should keep him employed and in a Cardinals uniform for years to come.
Weak side linebacker Orlando Huff, a six year veteran formerly of the Seahawks, established a career high of 69 tackles in 2005. That really shouldn't be a career high for any linebacker in any defense. As a contrast, strong safety Adrian Wilson registered 108 tackles last season. While tackles can sometimes be a subjective statistic, a position that is considered to be the "last line of defense" should most definitely not eclipse a starting linebacker by 39 tackles.
Beyond the three starters there is a lack of quality depth. Darryl Blackstock, projected as a possible starter going into last season had difficulty grasping the defense and adjusting to the speed of the game at the NFL level. Gerald Hayes has been a career back-up and has not been able to sustain the flashes of brilliance he showed at the University of Pittsburgh.
Issac Keys, Lance Mitchell, and Mark Brown are all young veterans that have speed and ability, but lack discipline. They have continue to show that the best showcase for their talents is special teams.
Brandon Johnson was drafted out of the University of Louisville in the 5th round of this year's draft. He's tall (6'5"), lean (227 pounds), and fast (4.6s in the 40). He seems to fit the mold of an Arizona linebacker, but it has yet to be proven if that's really a compliment.
The key to defensive coordinator Clancy Pendergast's scheme as far as linebackers are concerned seems to be speed and tenacity. The theory goes that if you hustle to the ball, can get there in a hurry, and continue to pursue that good things will happen. While the Cardinals finished in the top 10 in total defense last year, this theory has yet to translate into success on the field in terms of turnovers, third down efficiency, and, most importantly, victories.
However, it is important to note that this is the third year in Pendergast's system for all of the starters and most of the back-ups (the ones who weren't drafted in the last two years). It could very well be that the players lack the familiarity with the system to excel in it as opposed to simply not breaking it. Additionally, the return of Bertrand Berry to the line-up should force the flow of the play to the linebackers. Pendergast has succeeded as a coordinator everywhere he's been, so I'm inclined to continue to trust his system. Plus which, it's not as though I have a lot of choice in the matter.
The primary issue for Arizona in recent years has been its inability to succeed at the point of attack (both on offense and defense in the running game). In order for this to change, the players in the system will have to not only execute it more efficiently, but play above and beyond their natural abilities.
Their success in this endeavor, above all else, will determine their overall effectiveness.