I think they have all the tools to be there, maybe I'm missing something. I mean, Raven doesn't have wakeups but outside of that, what is she missing? As for Lobo, outside of slow specials I'm not sure what he's missing either. According to Ducky's Mu chart Raven does well against most of the commonly used characters/top tiers, and Lobo according to cap oxygen+fill pops has even matchups with nearly the entire cast. Maybe I'm being optimistic, but I think these characters have a real chance at occupying the bottom end of the top 10
It's not about how good they are, it's about how good everyone else is in comparison.
Imo (and in most peoples opinion), the following characters are certainly top 10: MMH, Aquaman, Flash, Bane, Zod, Batgirl, Batman, Wonder Woman
That's 8 right there, so the last 2 spots are up for grabs with the rest of the cast, and in order for Lobo or Raven (or Doomsday or Lex even) to compete for "top 10," they need to be better than these contenders for the #9 & 10 slots: Superman, Black Adam, Sinestro, Killer Frost, Zatanna, Deathstroke, Green Lantern.
The way I see it though, top 10 is a bill. You're right to think Lobo and Raven are strong characters, because they are. And so is over half the cast. Everyone I mentioned above (that's 19 characters) is strong. That's a testament to how well balanced Injustice is. If people want to concern themselves with who's in the "top whatever" I think it only makes sense to refocus that discussion to the top 15/20 - not being top 10 doesn't mean your character sucks in this game.