The six-foot-4, 268-pounder has missed time over his career with shoulder and ankle injuries.
Coming into 2005, Day was thought to be among the top tight end prospects in the country. A change in offensive systems forced him to adjust. Oregon went to a spread attack, which emphasized distributing the ball around.
"I think with my situation this year, since we went to a new unconventional offense, a spread offense, that threw a lot of people off," Day said at the combine.
Even though Day's receptions went down, he took something away from the experience.
"Definitely running routes in open field against linebackers and finding holes, things that wide receivers do," Day said.
The biggest question in his game has been blocking.
"Nobody's perfect," he said. "I definitely have weaknesses and I'm going to attack them."
Day had averaged 13.4 yards per reception the previous two seasons, but saw the number drop to 8.6. He also reached the end zone just one time in 10 games.
Despite the drop off, Day still had a productive college career. He caught 86 balls for 1,008 yards and 13 touchdowns.
"Day has very, very good speed and hands," said general manager Jerry Angelo. "He's a guy who can stretch the field."
The chances of Day not only making the roster but also challenging for major playing time are high. The Bears tight ends combined for 28 receptions for 250 yards and 4 touchdowns in 2005.
"It's not an indictment on the tight ends we have, the same guys we had last year, we want to create more competition at all positions," Angelo said.
"People started using tight end a little more and helping out the wide receivers a little more and opening the field up," Day said. "Five or six years ago, tight ends weren't as talked about as they are now and people are trying to draft them."
Although the Bears didn't draft Day, the hope is he can provide a pass-catching threat the team has lacked at the position for years.