Let me quote you his "run in" with Luke. I'm not sure everyone here has read it, and making allusions to it doesn't do it justice. Caedus was OWNED by luke. After becoming a sith, so that is his most powerful incarnation. He was NOWHERE near Luke's level. Read on:
" Caedus was glad to see Luke's lightsaber still hanging from its belt clip, but he took the precaution of slipping toward his desk, where he would have access to a dozen weapons and traps he had prepared in anticipation of just such a confrontation.
Luke jabbed a finger in Caedus's direction. "Now i understand why you've been avoiding me." His tone was even and soft, tbut there was no mistaking th ewrath in his Force aura. "And this time, you've finally crossed the line."
........ "In the next instant, Caedus found himself flying across teh cabin toward his observation bubble. Luke had not gestured, had not flinched, had not even shifted his gaze; he had simply grabbed Caedus in teh Force, and hurled him five meters into his char.
"Don't lie, " Luke started across the cabin. "I'm getting tired of it."
Caedus sprang out of the chair...or attempted to. Instead, he found himself strggling against an invisible weight He felt as if he were accelerating to lightspeed with a faulty inertial compensator.
"Luke, youve' gone mad." Cauedus reached for the controls on the arm of his chair, and discovered he couldn't even do that much. "You can't do this. I know you're having trouble dealing with Mara's death, but--"
....Keenly aware that all that stood between him and a quick death was Luke Skywalker's much strained sense of decency, Caedus let a little of his very real fear seep into the Force, just enough to seem properly alarmed.
...... Caedus would have shaken his head, save that it was still being held motionless with the Force
..... Then I'll take it for what it's worth, " Luke said. Leaving Caedus Force-pinned in his chair, he started toward the door. "I'll show myself out."
Caedus knew he would be freed as soon as Luke turned his concentration to something other than Force-pinning him--but that might take minutes, and Caedus needed to send in the Home Fleet now... he could not allow anyone, even Luke Skywalker, to humiliate him, and simply leave.
..... ""what?" Caedus was so shocked that he tried to rise--and found himself as unable to move as before. "You can't desert now. We can end this war!"
......
The door opened. Instead of stepping through, Luke faced Caedus and spoke in a very calm voice. "I'm sure you're not threatening the younglings."
He pointed at the base of Jacen's meditation chair and made a tapping motion with his finger. The pedestal gave a loud whumpf, and the seat dropped a quarter meter.
"Because you really don't want to see me angry." Luke made the tapping motion again. The pedesteal emitted a metallic shrek, and the seat dropped another quarter meter. "and i think you're smart enough to know that."
Luke tapped a last time, and the pedestal collapsed with a low loud crump, despositing Caedus on teh floor with his feet sticking out in front of him like a child.
"But if you want to try me, go ahead and make that threat."
Luke lowered his hand, and the weight vanished from Caedus's chest. He could have leapt up to attack--had he been that foolish--but Sith were not slaves to their emotions.
Okay, the ..... were dialogues i skipped. But Jacen is held motionless through something like 5 pages of dialogue. HOw can it even be argued that he can come ANYWHERE close to luke? You can't fight very well if you can't move.