The mobile defenceman was often Ottawa's best player but that didn't keep Kilrea from telling him when he thought Bell could be even better.
Bell served as a 67's captain, represented Canada at the world junior tournament and was named the CHL's top defenceman during those years. He didn't always understand why Kilrea was so hard on him.
Four years later, as he still tries to break through with the Toronto Maple Leafs, it's a little more clear.
"We definitely butted heads every once and awhile," he said Wednesday morning before the Maple Leafs took on Colorado. "It was a tough thing to go through at points but now I realize where his head was at and what he was doing.
"And I see why he's developed so many great players."
Kilrea wanted to see more consistency from Bell.
It's something Paul Maurice, his current coach with the Maple Leafs, will also be looking for.
The 23-year-old didn't play his first NHL game until last March, when he saw 14 minutes of ice time against Carolina. He never dreamed it would take so long.
"My expectations might have been a little bit unrealistic," said Bell. "Coming off a great year in Ottawa, there was talk of me making the (Maple Leafs) as a 20-year-old.
"I had it in my mind that it was going to happen and when it didn't, I was obviously disappointed."
Things only got worse as he struggled with the transition to the American Hockey League after being sent to St. John's.
Bell had been a minor-hockey standout while growing up in Ottawa before developing into an elite player with his hometown 67's. He simply assumed that success would follow him to the pro game.
"I thought the AHL would be a breeze," he said. "That's not the case. It's obviously a very, very good developmental league. I wasn't ready for the challenge of the AHL."
Suddenly, his dream of playing in the NHL seemed far away.
He spent two seasons in St. John's and was with the Marlies most of last year after the Maple Leafs moved their farm team to Toronto.
Bell played there under Maurice and started to make some strides with his game. It got him noticed and rewarded as Bell was called up three times before finally making his NHL debut.
By then, he realized the significance of the accomplishment.
"It's a difficult craft to learn," said Bell. "It was a big deal."
He arrived at training camp in September with a good chance to crack the roster and was well on his way to doing it before getting slashed in a pre-season game and suffering an ankle injury.
Bell made his return to a depleted Leafs blue-line on Saturday and played his second NHL game in a win over Calgary. Count his coach among those who were impressed with his game that night.
"I thought he really wanted the puck," said Maurice. "I thought that he looked like he was looking for it. He wanted to go back and be the first one to get it and skate a little bit with it.
"That's really what Brendan's game is. I thought he had a confidence with himself and I liked it."
Understandably, those were welcome words of praise for Bell.
But he's not about to let them go to his head. Bell currently rents an apartment in Toronto because he doesn't exactly have a ton of job security.
"I'm just waiting to see where things go," he said. "I'm playing it safe for the time being."
The Maple Leafs are currently without injured defencemen Pavel Kubina, Carlo Colaiacovo, Staffan Kronwall and Andy Wozniewski. That makes it tough to handicap Bell's long-term chances of staying with the Leafs, but he realizes his play now will have a big say in it.
"Anytime you get a chance to play, you've got to take advantage of it," said Bell. "When opportunity comes knocking, you've got to be there for it."
It's something Kilrea had tried to instil in him as a teenager.
He can still hear his former coach's words now.
"You've got to show up to play every night and work harder than every other guy in that room," said Bell. "They can never ask more of you than that."