"I think that was the last straw," Del Rio said Wednesday.
Del Rio acknowledged that the timing wasn't ideal. Garrard was released five days before the opener and just a couple of hours after he was introduced as the starting quarterback at a chamber of commerce luncheon put together to help promote the team.
"I don't like the idea that the timing went down the way it did, but it did," Del Rio said. "Ultimately as an organization we've got to make decisions when they're not comfortable and make the best decision for the football team. I do believe we've done that.
"Sometimes it just doesn't fall the way you'd like it to in terms of timelines and things you have commitments to. From that standpoint, I would prefer it have gone down differently. You deal with things as you have to. We took that one to the last possible minute because it was something that we continued to hold out hope for."
Garrard might have a new team soon. His agent, Al Irby, sent a text to ESPN NFL Insider Adam Schefter on Thursday saying, "We are moving at rapid speed. Hope to know our direction next week."
Garrard struggled in the preseason, completing 50 percent of his passes for 216 yards, with no touchdowns and an interception. He was sacked three times.
Luke McCown, who will start Sunday when the Jaguars host rival Tennessee, was better in the preseason, though it came mostly against second- and third-teamers. He completed 12 of 18 passes for 133 yards and two scores. He didn't have a turnover and didn't take a sack.
Nonetheless, the Jaguars settled on Garrard during final roster cuts last weekend. They released an updated depth chart Monday, with Garrard as the starter, rookie Blaine Gabbert as the backup and McCown as No. 3.
One two-hour workout shuffled everything. Players called the practice the worst they had seen in some time. For Del Rio, who grew tired of Garrard's inconsistent ways last season, that was enough to go to general manager Gene Smith and team owner Wayne Weaver and get permission to cut Garrard.
"It was a shocking thing," guard Uche Nwaneri said. "That's the nature of the business. You never know when your number's going to come up. We love Dave here. He's done a lot here, been to battle with him a lot. I'll always have a spot for him in my heart. That's the decision the front office made.
"Luke is the guy now, and everyone's going to rally around him."
McCown hasn't started since the 2007 season finale and hasn't played since Week 2 of last season.
Team leaders called a players-only meeting Wednesday to help everyone understand the decision and move forward.
"We knew the changing of the guard was coming," tight end Marcedes Lewis said. "We drafted Blaine Gabbert with the 10th pick. We just didn't know when the changing of the guard would come. Obviously, it's now and it's with Luke. This definitely is going to test the maturity of out team."
McCown's maturity, too.
The 30-year-old McCown has completed 49 percent of his passes for 1,739 yards, with nine touchdowns and 10 interceptions. He spent a year in Cleveland and four seasons in Tampa Bay before signing with Jacksonville in 2009.
"I've never looked at myself and said I'm a career backup," McCown said. "I always, in my heart of hearts, knew I would get another opportunity."
McCown probably would have replaced Garrard early last season. Garrard threw four interceptions at San Diego in Week 2 and was benched in favor of McCown. But McCown tore the anterior cruciate ligament in his left knee and needed season-ending surgery. Garrard returned to the game and kept his job.
"I'll take this in stride," he said. "I'm excited about it. It's an opportunity I've waited for, prepared for a long time. ... It's like riding a bike. You step back in and you look the other 10 men in the huddle in the eyes and you grab heads and you say, 'Let's go.' "
Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.