Two different Stats are responsible for the Power and Condition Meta Builds in WvW.

 Concentration Stat boosts the Power Build and Expertise the Condition Build. Don't ever forget these 2 Rules!

    In the early days of Guild Wars 2 these 2 rules were total different than now, 10 years later. For Zerg Fights were the Power/Toughness/Vitality and the Healing Power for the Front-line and Power/Precision/Ferocity for the back-line and roaming. There weren't any "Condition Gods" builds at the early days of GW2 and the condition Stat became serious threat when they created perplexity condition (I still remember my Mesmer kill everyone with these 25 stacks of perplexity.It was the First "Condition God" Build of GW2 😂).

    Also these days we could pick more than 3 Specializations as you can see on the one of my most used builds of the early days of GW2 for my front-line Guardian because i used the radiance Specialization to blind the enemies at the beginning of the fight and to renew the F1 virtue after enemies death (This was my secret for long time 😋). This image taken 15 August of 2013.

Tsekouri's Front-line Guardian Build. 15  August 2013

    But, time passed and now after 3 expansions of GW2 ( i really don't remember when they changed this old system ) we can choose only between 3 specializations. Also Anet made clear what matters more for these 2 different Fight types inside WvW ( Zerg and Roaming ),  their 2 different meta builds ( Power  Build and Condition Build ) and their Stats that boost each one of these 2 different Build meta types.
    After 10 years it's more than clear that if someone wants to play in a Zerg Fight his/her weapon/armor/food/traits or Roaming with a Power Build he/she should focus to boost the Concentration Stat that increase the time of Boons that apply or earn to others his/her self. In GW2 every time you apply a boon to others it benefits yourself too!
    And if someone wants to play with a Condition Build alone as Roamer or inside a Zerg he/she should focus to maximize the Expertise Stat that increases the condition duration (more-time => more condition stacks on your enemies).
In conclusion... The rules in WvW for your 2022 meta Builds are simple. 
  1. Power Build = Concentration.
  2. Condition Build = Expertise.
p.s. What about a Mixed Build with good Concentration and Expertise with Celestial Armor/Weapons? I think the mixed builds are more powerful in small scale fights like havoc groups that ofc they can do everything inside WvW Maps, including to capture the Stonemist Keep because inside these small fights all members have multiple roles to play and support.