That's basically how he seems to be managing things. If I had to guess, it is just the result of Oomori being enamored with OPness and the underdog trope.
Bell's stats do have (or at least had) the purpose of having him punch above his league. As a low Level 3 he had Level 4 speed, as a mid Level 3 his entire status was Level 4 tier, as a new Level 4 he had Level 5 speed and so on. He had indeed been able to fight those above his level, even early on.
Only reason he was always struggling was because his enemies were overall better. Phryne had higher stats in everything, with even Bell's speed under Haruhime's level boost being slightly lower, and was obviously more skilled. Lyd is high Level 5 tier. Against Dix his status, even if in the same league as the hunter's, was still lower, not to mention Dix was way more skilled. Asterius, well, Level 7. And the Juggernaut was faster than him.
The thing is that Oomori hasn't been respecting it recently. Van being a threat even when Bell focused on him, and then it being said he had lost against him from time to time. And everyone do treating him as just a Level 5, when before you at least had characters note his prowess was abnormally high.
Of course, you can say it was to force Bell into the "scenery of despair" Oomori was going for, but he could very well have Bell dominate Van and the rest, and then have him be crushed by the executives. Though, Oomori isn't a stranger to having a character dramatically underperform for the sake of having things go how he wants them to. He had Bete, a Level 6, have troubles dealing with a few dozens of assassins, of whom the strongest was just Level 3, in SO8. But then he made a bunch of Level 6s defeat 10,000 soldiers each, soldiers among which there were some Level 2s and 3s in EF.
He also loves for Bell to be the "underdog", so maybe he just didn't want him overpowering "elite" Level 4s, although that is exactly what should have happened logically. He simply goes along with such things even if they are contradictory. Like him saying several times that Bell has no talent at all, but also that Bell is such a quick learner he impressed even Ais and Ryuu. The guy just can't settle with one line of thought.
So, in paper, yes, Bell should by now be above his level, even with zero in stats, based on early evidence. But in practice? It will be whatever Oomori feels like doing. Hell, Bell's next defeat may very well come from a Level 4 at this point.