Actually, I went and pulled the data to check this also. It’s not a small fraction. For the last 1000 losses of the Proteus, just under 1/3rd of them have the Drone Synthesis Projector fitted (ie. not in the subsystem hangar, but fit to the ship):
Noting, that we have to assume that the use of the offensive modules across losses is a reflection of use, and not strength of fit (ie. We have to assume that the hybrid is being used more, not that hybrid fits are weaker than drone fits so die more, and therefore should be buffed instead). I think that’s a pretty safe assumption to make.
So it isn’t a small percentage and with only 3 possible offensive modules, almost 1/3rd of losses being drone fits isn’t an under use in my book.
In addition, comparing the total kills in pvp that involve the Proteus, the numbers even post T3C nerf are still around 10000 kills per month. That’s still well over 300 kills per day with a Proteus on the attackers list, and if the assumption above is correct, then about 1/3rd of the time (or over 100 kills every single day) involve a drone bonused Proteus.
It’s being used fine as a drone ship.
Lastly, looking at the kill:loss ratio of the Proteus, despite the nerf, it is still averaging in the range of 20-25 kills for every single loss, with almost a 1/3rd of the time being fit for drones. Compare that to the Gila and the Ishtar, which both have a K:D ratio under 5, and yet they are considered strong drone ships, and the Proteus as a drone boat should be weaker than the PIshtar (and it may be, not making a judgement on that, just that as a principle of T2 to T3, the T3 as a flexible generalist ship should be weaker than the specialised T2 ship):
Drone based proteus is doing fine in pvp.