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It has been a long and winding road but the San Francisco 49ers defense overhaul is complete with the selection of defensive end Nick Bosa in the 2019 NFL Draft on Thursday.

When John Lynch took control of the 49ers, the team was in shambles. Head coach Kyle Shanahan would go a long way towards fixing the offense. The defense was a different matter.

There were a few young pieces with potential. Defensive tackles DeForest Buckner and Arik Armstead along with safety Jaquiski Tartt were on the team. They weren't finished projects. They needed development. There were no great veterans either. In fact, there wasn't a single Pro Bowl caliber defender on the roster at the time Lynch was made general manager. The rest of the defense would have to be acquired.

Since then, Buckner has developed into one of the top players at his position, former Pro Bowlers, cornerback Richard Sherman and Jason Verrett and linebacker Kwon Alexander, were signed in free agency while potential Pro Bowl caliber players, linebacker Fred Warner and Bosa, were drafted and Pro Bowl defensive end Dee Ford was obtained via trade.

The 49ers line up in nickel more than any other formation defensively. Completing that lineup would be Armstead or Solomon Thomas at the other defensive tackle position, Ahkello Witherspoon as the third cornerback (who covers slot is T.B.D.), Tartt as the strong safety and either Jimmie Ward or Adrian Colbert at free safety.

49ers 2019 Defense
CB Sherman DE Bosa DT Armstead/Thomas DT Buckner DE Ford CB Witherspoon
CB Verrett LB Warner LB Alexander
SS Tartt FS Ward/Colbert
*Base formation: Thomas or Armstead slide outside to DE, Ford or Mark Nzeocha play the third linebacker.

Lynch was hired in January 2017. In just more than two years, the 49ers have developed a pro bowler, signed three pro bowlers, traded for a pro bowler and drafted at least two potential pro bowlers on the defensive side of the ball.

The 49ers didn't just target talent blindly, however. They sought out players who could transform the defense into a fast unit that gets to the quarterback and fits together perfectly like one big puzzle.

Lynch, Shanahan, defensive coordinator Robert Saleh and new 49ers players have all been heard repeating the phrase, "all gas, no brakes" in recent weeks. It drives home the 49ers' clear objective this offseason of improving the pass rush. Bosa was the final piece and the 49ers know it.

"You're going to fit right in," Saleh told Bosa on the phone on Thursday. "Just come with that mindset. Let's get after the passer ... all gas brother."

All gas indeed. The 49ers should be a lot more aggressive defensively this season. The defensive line should be one of the best in the league. Having a good rush from both edges thanks to Ford and Bosa, along with a great interior push with Buckner is rare. Offenses will have to pick their poison.

"I think opposing O-lines should be pretty scared," Bosa said to 49ers team reporter Keiana Martin on Thursday.

Scared might be going too far but this isn't the nearly empty cupboard 2017 defense or the work in progress 2018 defense. This is the finished product.

That winding road has straightened, a drag strip formed, and the 49ers are a hot rod ready to hit the gas and put the pedal to the floor. Maybe that's cheesy to say, but it's true too. This 49ers defense is primed.