That's a tricky question.
From a narrative standpoint, I think we're meant to believe he did everything he could against Dumas. Khun was "dead" and Rak massacred. He was up against one of the strongest High Rankers in the Tower, someone who had already negged him beforehand (alongside Jinsung, Yama and Karaka). Even he did say that none of his attacks worked on Dumas. He was so desperate that he had no choice but to rely on Dragon Tiger Gate, a technique he had never used before and that only saw his master do once. Given the entire context, it doesn't make any sense to believe he was holding back.
Yet it's true that if we look at all the tools he should have, he didn't go all-out. He didn't use the 1st Thorn Ignition (Stab), he didn't use the Second Thorn, he didn't use his Revolution mode (horns), nor the external transformation of Red/Blue Thryssa or the souls. Aside from Leviathan's power, the 1st Thorn amp, and Shinwonryu, he hardly used anything else.
So dunno. SIU's writing regarding the usage of Baam's powers is quite messy, to say the least. Baam himself also thinks he's weaker than Jinsung and White (CC Tier fighters), both far weaker than Dumas. Personally, I'm going to assume that his body is not strong enough to handle all the powers he has simultaneously. If he uses as much of Levi's power as he can, it doesn't leave much room for him to use the rest of his powers.
So with that mind, he's strong enough to destroy the average BH (like Wiwi), but not strong enough to have a guaranteed win against a CC Tier fighter. I'd put him on the lower end of the CC Tier as of now (beneath Prime White and peak Jinsung). Gets easily massacred by Dumas, as we saw on-screen already.
