Much of the focus on the Steelers' offseason has been on the offense. After all, the team used its first four picks in the draft on offense, and it was the offensive side of the ball on which the team struggled the most in 2020.
But there are changes on defense, as well. Outside linebacker Bud Dupree, cornerback Steven Nelson and nickel corner Mike Hilton are all gone, leaving three holes to fill.
Alex Highsmith was selected in the third round of last year's draft and took over for Dupree opposite T.J. Watt over the final five games of the season after Dupree was lost to a torn ACL.
There seems to be a belief that Watt's production fell off without Dupree opposite him, but that wasn't really the case. The NFL sack leader with 15 last season had four sacks in four regular season games after Dupree was lost. And he also had eight of his 41 quarterback hits in those games, sitting out the meaningless regular season finale for the Steelers, who had already wrapped up the division title.
And Highsmith was effective, as well, down the stretch, recording a sack and five quarterback hits in those five games.
They were all part of a defensive front that had a 12.4 percent pressure rate on passing downs last season. That was the highest percentage in the league since 2010 and helped the Steelers lead the league in sacks with 56 for the fourth consecutive season, something that had never been done before.
The Steelers feel Highsmith will adequately replace Dupree, and they feel they have the guys to replace Nelson and Hilton, as well. But the biggest addition to the defense might be the return of inside linebacker Devin Bush.
Bush was lost five games into the 2020 season to a torn ACL suffered late in a 38-7 rout of the Browns at Heinz Field in Week 6. To that point, he had played every defensive snap for the team.
The Steelers wanted to use more dime defensive looks last season trusting their front four of Watt, Dupree, Cam Heyward and Stephon Tuitt to generate a pass rush, but without Bush were unable to do so as much as they would have liked.
He's their X-factor linebacker.
They still ran a dime defense 12 percent of the time, which was higher than league average. But the majority of their time in a true dime came when they still had Bush available. After that, they were forced to use unproven commodities such as Marcus Allen, Robert Spillane, Ulysees Gilbert or midseason pickup Avery Williamson as a dime linebacker.
That led to the Steelers playing more nickel than dime last season. They were in the nickel defense 36 percent of the time, making it their primary defensive package -- the base 3-4 defense accounted for 31 percent of their defensive snaps.
Bush has been back and practicing with the team at OTAs, which continue this week, and is on pace for a healthy return to the lineup this year.
He allowed 14 completions on 22 pass attempts and one touchdown in his coverage last season, a completion percentage of 63.6 percent. Opponents were 16 of 21 when targeting Williamson, 8 of 10 targeting Allen, 16 of 30 targeting Spillane and 22 of 35 when throwing at Williams.
But there is a reason the Steelers traded up to acquire Bush with the 10th pick in the 2019 draft. His speed -- he ran in the low 4.4s at the NFL Scouting Combine -- is rare for the position.
And while young linebackers often struggle in coverage, his speed gives him a big leg up to get better in coverage. Bush's coverage early last season was slightly better overall than what he did as a rookie in 2019, when he allowed 46 completions on 68 pass attempts in his coverage to go along with five touchdown passes.
If Bush can return and continue his improvement in that area, which is expected, a massive improvement could come in Year 3.
For example, the 49ers' Fred Warner, who many regard as one of the top inside linebackers in the league after a breakout season, saw the passer rating against him fall from 86.2 in his second season to 69.7 in 2020, his third year in the NFL.
Chicago's Roquan Smith, another top young linebacker, has seen his completion percentage allowed fall from 73.2 percent as a rookie in 2018 to 63.3 percent last season. More importantly, his yards per completion has gone from 9.8 in his first season to 5.8 last year.
And while many laud the Buccaneers' Devin White as being a big playmaker for Tampa Bay's defense, he allowed an 83.3 percent completion percentage and 109.6 passer rating in his coverage last season. It's actually veteran Lavonte David, who allowed 6.0 yards per completion in coverage, who is the more polished and better player and allows White to roam a little more freely.
The return and potential improvement of Bush that could make a big difference for the Steelers.
His healthy return would allow the Steelers to do what they prefer, which is to rush the quarterback with their front four and have seven players dropping into coverage.
If that happens and his coverage continues to improve, the defense could be as dangerous as it was in 2020. After all, the Steelers allowed an average of 285.2 yards per game last season with Bush in the lineup and 315.2 without him.