You dont have legendary gloves, it does actually matter on a tank, look at the link above
Warcraft Logs - Combat Analysis for Warcraft there is a 60k dkp difference in the best warrior without vs the best warrior with (this is on guarm)
i am looking at your log for Guarm
Warcraft Logs - Combat Analysis for Warcraft - berossus a warrior without legendary gloves that has +/- 1 ilevel from yours
Warcraft Logs - Combat Analysis for Warcraft - your log for the same boss
key differences:
1.their fight took 2:46 vs your 4:39 - not your fault, thats raid dps's primary responsibility. DPS doing a better job would allow you a higher "ranking"
2.you had 85 devastates/37 shield slams, the warrior I'm comparing you to had 2 minutes less time in the fight and had 70/30. That says to me that you can spend more time spamming devastate. you only had 15 more over 2 minutes which is fairly low.
3. you had 42 IPs that shielded for 27 million, he had 24 casts and shielded for 20 million. thats only 7 million more with double the casts. His average IP was ~200k more than yours (this can be attributed to str being lower by ~ 3k not utilizing ultimatum/vengeance procs properly) the more IP casts can be devastates which lead to more shield slams.
4. You have no haste enchants, no Neck enchant, no back enchant, replace the gem in your ring with sabers eye of str its going to be a primary piece of gear for you for a long time, at least enchant it and gem it properly.
5. get rid of your crit chance replace it with haste, all the crit you need you can get from StB. the haste will give you more shield slams especially over a 4.3 minute fight.
I can dig deeper later, but he did ~200k which is probably about as much as your going to do at your gear level without gloves, with gloves you could be around 240ish.
