Palhares is frustrating. He's a straight killer. His Jiu Jitsu is vicious, and he has the wrestling good enough to be able to get a lot of dudes to the mat. There's that video on the net of him rolling, and mauling Mayhem, pre-Mayhem's woeful UFC performances and breakdown. Mayhem is seen as one of those dudes that's very hard to takedown, and even harder to submit, but Palhares handled him like a child, and easily submitted him.
Harris has incredible ability, the issue comes with his fight smarts. His fight IQ is one of the worst in MMA, and once he feels he's losing a fight he gives up. It was showcased mainly against Marquardt. Went for the leg, thought that like Drwal and Linhares he was just going to give in and have his knee wrecked, when that didn't occur, and the unthinkable happened, Marquardt escaped, Paul Harris cries to the ref, and gets himself punched in the face, really hard. Also, in the Belcher fight, he was expecting to dominate on the ground, but when Belcher showcased his dominance and continually escaped the leg locks, Palhares immediately gave up, and got TKO'd.
It's not a lack of ability, Palhares is one hell of a fighter, it's his mentality that's the issue, and I think that's unlikely to ever change. Despite having the ability, he'll never be a champion.
That's the perfect description of Palhares and because of all these great assets he possesses, Murilo Bustamante still believes he could develop his fight IQ and also get rid of his insecurity when the plan does not go exactly like expected.