I don’t have a horse in this race because I’m just a solo delver now. But I have a lot of previous experience in both. My suspicion is that any top-tier PvPer would be able to become a top-tier Raider in a reasonable amount of time. But the reverse is not necessarily true. Sure, plenty top-tier raiders might be Gladiator-capable, but I bet it’s not all, or not even most. PvE has a level of rote that you just don’t find in PvP.
Of course, being a top-tier raid LEADER is a different story. I don’t claim that every Gladiator would be capable of figuring out how to lead a raid to a world first or even world 50th.