First part correct, second part is an exaggeration on your part. The tweet just said that this should be a wake-up call to Williams and the D-line as a whole about keeping their weight in check. It could be a coaching problem but thats not what i got from the tweet.
Why is it an exaggeration? What makes you think the Cards have played decent defense since 2007?
In 2007 they ranked 27th in points allowed.
In 2008 they gave up 36 passing Touchdowns
In those two seasons they gave up 825 points and that wasn't playing with an offense that went 3 and out very often. (Well maybe Warner and the offense scored too fast so the D didn't get enough rest.)
Last year they gave up highest or second highest season passing totals to 5 different QBs. They let Vince Young throw for 387 yards, VINCE YOUNG! They let two no name running backs from bad teams gouge them for big yards and tried to blow the big leads Warner and the offense gave them numerous times.
They gave up almost 100 points in the two playoff games and then, after getting rid of all the me first players there was the Atlanta game this season where they just got steamrolled.
All of that is fact not exaggeration.