The 49ers defense could look much different next season under Robert Saleh.

Of all the players he coached on the 49ers from 2017 to 2020, only two remain under contract: Fred Warner and Nick Bosa. The rest are players who were acquired after he left to coach the Jets.

Now that Saleh is back, he will have a major voice when it comes to the defensive personnel. And it’s possible that he may not see some of the current players as fits for what he wants to do.

Take Leonard Floyd, for example. The 49ers signed him last year to a two-year contract because assistant head coach Brandon Staley worked with him in the past and recommended him to the front office. Staley most likely will not return this year, which means Floyd might not, either. He’s horrible against the run and he’ll be 33 next season. If he doesn’t get released, he might have to take a pay cut and a demotion because he can’t start at defensive end for a team that wants to have a good run defense.

Then there are Maliek Collins, Yetur Gross-Matos and Jordan Elliott — three other defensive linemen the 49ers signed last year. All of them were disappointments and none of them have guaranteed money left on their deals. Which means the 49ers cut release any of them or all three.

I’m guessing the 49ers will re-sign Dre Greenlaw to a one-year deal considering Robert Saleh knows him and had a hand in drafting and developing him.

I’m also guessing the 49ers won’t re-sign Talanoa Hufanga or Charvarius Ward because they were acquired after Saleh left and he doesn’t know them. Don’t be surprised if they follow DeMeco Ryans to the Houston Texans.

In the draft, look for Saleh to add an explosive edge-rusher, a run-stuffing defensive tackle and a three-down linebacker who can replace Greenlaw in a year, or the next time he gets injured.

Overall, expect Saleh to add speed to the defensive line, the linebacker corps and the secondary. The 49ers are much slower as a team than they were when he was here last.