Pittsburgh, which started the night with the 20th overall pick, moved up 10 spots in a trade with the Denver Broncos to select Bush, the former Michigan star and new Steelers inside linebacker.
"We thought that highly of him," Colbert said. "It was easy in our minds to pick him with the 10th pick. We did what we had to do."
Colbert relinquished the 20th and 52nd overall picks in 2019 and a third-rounder in 2020 in exchange for Denver's No. 10 pick. Colbert said he wouldn't have executed the trade unless he walked away with two Day 2 picks. The team held on to two third-rounders -- one courtesy of the Antonio Brown trade in March -- and has eight remaining.
The franchise's last splashy draft-day move came in 2003, when Pittsburgh moved up 11 spots to take future Hall of Fame safety Troy Polamalu.
The trade gave the Steelers their first top-10 overall selection since taking receiver Plaxico Burress eighth overall in the 2000 draft. Bush is the seventh consecutive defensive player to be selected by the Steelers in the first round.
Bush, at 234 pounds, was considered one of the draft's best all-around players because of his versatility, instincts and speed.
Talking with Pittsburgh media via conference call, Bush said coach Mike Tomlin called Thursday night to ask if he wanted to be a Steeler, to which he replied, "Hell yeah, coach. I'm ready."
Tomlin called Bush an "all-situations player" and said he is "equally fired up" about his intangibles. The Steelers assigned three coaches and four scouts to dig into Bush. Each evaluator graded him as a first-rounder.
"I think I'm a good fit. I love to win," Bush said. "This team wants to win, and I'm a guy who loves to win. ... I'm a guy that can play sideline to sideline. I can cover. I can blitz. I can play the run, play the pass."
Bush understands the gravity of replacing Ryan Shazier, the Pro Bowler who suffered a severe spinal injury in December 2017.
Bush called Shazier a "great player" who will be back on the field and said he hopes to see him soon. Both are from the South Florida area.
But the new linebacker made clear that he isn't comparing himself to anyone. "I'm just ready to be Devin Bush," he said.