The short answer to this question is: No, not really.
A friend of mine over on the Tennessee Titan's page (Music City Miracles) just made a post regarding the o-line for their team which is under heavy fire for their "garbage play" which brought my attention to an interesting stats page called Advanced NFL Stats.com; to view the relevant statistics you can go to http://wp.advancednflstats.com/teamOL.php?year=2007&season=all and work your way from year to year.
From the time Grimm started in 2007 the Cardinal's O-line rates as 16th best in the NFL, this remained steady going on into 2008. By 2009 they are rated as the #1 offensive line in the NFL. 2010 sees it drop down to 9th with a sudden and sharp decline to 29th in '11 and well here we are in 2012 at 31st.
Grimm is a good coach, so good that he was considered to be the head coach of the Bears back in 2004. You don't simply lose the ability to be an effective coach or coordinator over night due to some mystical curse placed upon you. If I am to believe somehow Grimm is at fault here then I must assume the following must be true:
You have a master chef who is known for making the most exquisite gourmet meals anyone has ever eaten and you ask him to make you one of those meals. Simple enough task, now you point him to the kitchen which has the following ingredients: mud, sticks and worms. The master chef provides you with a horrible meal and now it is HIS FAULT he could not make something delicious from mud, sticks and worms.
You might want to say that blaming a lack of talent is a cop out, but that just doesn't hold water if the same coach has produced favorable results for your team in the past. You do the best with the ingredients you are given.
If you are interested in the post on the Titans go here: http://www.musiccitymiracles.com/2012/10/8/3476334/speaking-of-that-horrible-o-line