The duo has split reps during spring ball, down to the point of alternating days in running with the first team, according to Fedora.
"We've had great competition at that position," Heckendorf said on Wednesday. "One day one guy is ahead and the next day the other; it's been a back-and-forth battle. We're going to be, on offense, as good as our quarterback will allow us to be. We put a lot on that position and to have that kind of competition this spring is going to make our football team better."
Heckendorf, who briefly worked as the tight ends coach at Arkansas State for the month of January, returned to Chapel Hill after spending the previous three years at UNC as an offensive player development assistant, primarily working with the quarterbacks. As such, he's familiar with both Williams and Trubisky and their capabilities.
The quarterback competition has led to significant improvement for both players this spring, according to Heckendorf.
"They both have been pushed and sometimes that's what you need," he said. "You need that guy that's breathing down your neck to get you out of your comfort zone to take your game to another level, whether that's on the field or in the classroom studying."
For Williams, the emphasis this offseason has been on fine-tuning his mechanics and improving consistency in throwing the ball. The junior quarterback completed 65.7 percent of his passes against Virginia Tech and 74.1 percent against Old Dominion, but only managed a 53.2 completion percentage in his other four starts.
"When he's mechanically sound on throws, he's as good as anybody," Heckendorf said. "But there are times when he lets his mechanics fall off a little bit and he knows that's the weakness he has in his game that he needs to continue to improve upon."
Heckendorf indicated that Williams has done a good job focusing in individual periods on getting his back hip through, transferring his weight to his left side and not falling away on throws.
Improvement comes from repetition and being aware of the mechanics involved, according to Heckendorf.
"Sometimes last fall I don't think he was always conscious that he was doing it," he said. "You go down and you look at it in the film room and you say, ‘Okay, here's what it is, here's the problem.' Find the problem, address it and give him a way to fix it and a plan to go about attacking it. That's what we've done this spring."
While observers have seen plenty of film on Williams, Trubisky remains a mystery outside of a handful of spring scrimmages open to the public.
"Mitch is a very even-keeled guy; he plays with a lot of poise," Heckendorf said. "He's a guy that the stage doesn't rattle him. At least it hasn't in the live scrimmages that we've had and the different situations that we've been able to put him in to try to test that.
"But he's got a great understanding of the offense. He's a passer first, but he's got some athletic ability - probably more than people give him credit for - to be a threat in the run game, to pull it when he needs to."
Heckendorf said that Trubisky was "pretty quick," adding that he didn't know who would win if the quarterback duo lined up for a foot race.
"They both bring the element of the running quarterback to the table, which adds a dimension to our offense," Heckendorf said. "When that element is there, it's one more thing defenses have to prepare for and worry about."
With regard to the intensity of the quarterback competition, Heckendorf's message to the players has been consistent: "It's great competition, but at the end of the day, we're all Tar Heels."
"This quarterback room has got to be a tight unit," he continued. "We've got to help each other. When one guy is out there, the other guy has got to be his biggest fan and his biggest supporter. When the other guy is out there, it's got to be the same way. And, at times, I know that's hard because they are competing and they both want the position so bad and they both want to be the guy. But the reality is that only one can be out there at a time."
If Bryn Renner's season-ending shoulder injury at N.C. State last season proved anything, it's that even the backup has to prepare as if he's the starter.
While Fedora acknowledged last Friday in Greensboro that Williams remained slightly ahead of Trubisky in the pecking order, a final decision likely won't be made until late August.
"In the end, the best guy will lead us on Saturdays," Heckendorf said.