It's difficult to train for all-round climbing, as the demands are sometimes conflicting. Become stronger, and you'll lose your endurance. Train endurance and you'll end up weaker. But the sticking point is almost certainly 'power-endurance' - that is, being able to do moves repeatedly just under your max without pumping out. The hardest boulder problems I've done are aeons harder than anything I've ever encountered on a route. There are of course other components playing into this - a long trad background has lead to an aversion to anything but onsighting, and I've had to actively repurpose my brain to a sport-climbing mentality. But I've never attempted anything harder than UK Tech 6a on a route, say about V1 or V2, yet bouldered up to V6. That's an astronomical difference, and I'm not even a boulderer.
I can only conclude that I probably have sufficient power, but lousy power endurance. Or, somewhat less palatable, maybe I'm simply too scared to climb to my limit on trad, and too lazy to work sport routes?