The 49ers believe the pass rush was the problem with the team's defense late in the season.
The proof came in how the 49ers executed their draft plan.
The 49ers return their top five cornerbacks from a year ago. The pass defense was exceptional for most of the season and finished the regular season ranked No. 4 in the league, allowing just 200.2 yards passing per game.
The 49ers were the best in the NFL at preventing the big play. They were the only team in the NFL that did not allow a scoring pass of 40 yards or more during the regular season.
But the 49ers' pass defense can also be separated into two categories: Healthy Justin Smith and Post-injury Justin Smith.
In the first 13 1/2 games of the season with Smith healthy, the 49ers allowed 183.0 yards passing per game, a statistic that accounts for sack yardage. Aldon Smith, who played with a shoulder injury late in the season, had all 19.5 sacks up to that point.
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Justin Smith sat out the final 2 1/2 regular-season games with a partially torn triceps tendon. He returned at less than full strength for the playoffs. In those 5 1/2 games, the 49ers defense surrendered 300 yards passing per game. Aldon Smith, the main beneficiary of Justin Smith's disruptive style, was shut out in the sack department.
The opponent passer rating with a healthy Justin Smith was 74.6. After Smith's tendon tear, quarterbacks carved up the 49ers with a 102.1 rating.
Obviously, the 49ers do not hold the secondary accountable. The 49ers invested two of their top four draft picks on rotational pass rushers.
Yes, the traded up in the first round for LSU safety Eric Reid. He is penciled in to take over the starting role from All-Pro Dashon Goldson, who signed with the Tampa Bay Buccaneers as a free agent. But the 49ers eschewed cornerbacks in favor of other positions.
The 49ers selected defensive lineman Cornellius "Tank" Carradine with the 40th pick. Carradine can play every line spot in the nickel defense. He is also projected as the Justin Smith's eventual replacement.
The 49ers selected Carradine over cornerbacks Jonathan Banks (Mississippi State), David Amerson (North Carolina State) and Jamar Taylor (Boise State), who were chosen before the 49ers went with tight end Vance McDonald at No. 55.
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And the 49ers chose McDonald instead of cornerbacks Robert Alford (Southeastern Louisiana), Leon McFadden (San Diego State), Tyrann Mathieu (LSU) and Blidi Wreh-Wilson (Connecticut).
The 49ers' next pick was outside linebacker Corey Lemonier of Auburn. He can back up Aldon Smith and Ahmad Brooks, as well as line up at defensive end in pass-rush situations.
This shows the 49ers are comfortable with cornerbacks Carlos Rogers, Tarell Brown, Chris Culliver, Tramaine Brock, Perrish Cox and veteran pickup Nnamdi Asomugha.
The 49ers believed the best way to improve the pass defense was to create better depth among the team's pass-rushers.