I would've agreed with you 100% a few weeks ago. However, Holl was playing quite well with Brodie when they were paired up for those several games. I'm still not a huge Holl fan, but I'm not willing to let Muzzin off the hook completely for this. It's not like he's been lights out. Is his decline progressing faster than expected or does he just need the right partner to cover up his shortcomings where he didn't need it before.
Personally, this is the D I'd be going with until injuries arise, or one or more of the pairings are exposed...
Rielly - Lyubushkin
Muzzin - Brodie
Giordano - Liljegren
#7 Sandin
#8 Holl