Bit of a dilemma...

So, I have a Dorcas in one of my main teams who just so happens to work very well with my Micaiah, Veronica and Silvia. However, I've only NOW noticed that he has some awful IVs: -Res, +Spd. I'm still working with only his base kit right now, even now with him at level 40. So, my question is this; do I bother to keep him or not?