I guess depending which tank You are.
Check Your buff uptimes:
Go to Buffs Gained and click on # on which spells You want to see uptimes.
Example Horn of Winter / Battle Shout have to be up all time.
Blade Barrier (for DK) should be as close as possible to 100% etc.
Go to Buffs gained but check Debufs with # as its on boss.
Example Thunderclap, Scarlet Fever etc.
So basically choose your desired kill/wipe then from drop-down Players->Class->Player
And check like
"Damage by Spell" where You can check miss / parry / dodge / apsorb
"Buffs Gained" to improve Your + other Player spell Buff uptime
"Buffs cast" only Your buff casts
Plus You can take from drop-down Creatures ->Boss
and check buffs debuffs on Boss.
If at first you don't succeed, you are running about average