I asked in another thread about combat dummies & expertise. If a PvP dummy demonstrated the importance of expertise (recruit gear) over other stats, that might make it more obvious to the skeptics.
Also, does expertise apply in dueling? If yes, you could help educate someone by doing a very controlled duel e.g. standing still and methodically taking turns. You could do one duel with the PvE gear and one with recruit and observe the difference in damage done/taken.
Can anyone confirm or refute the idea that expertise applies in duels and/or open world PvP?
Expertise says increases damage done to players and I'm not sure why we have a reason to believe that won't affect duels/open world PvP. I mean, anything's possible, but there's just no reason to believe otherwise without proof on the contrary.
The PvP dummy does not appear to actually take Expertise into account. On my WH characer with 1260 Expertise, I use FL and get that it does like 20% less damage than its tooltip with. However, I switch to an alt and with 0 Expertise and it still looks like I do 20% less damage than tooltip on the same dummy. i can't quite prove it yet because my alt's attack have a range of damage so I haven't worked out all the ranges, but it should be pretty trivial for anyone with a SI alt with 0 expertise to verify.