LOS ANGELES -- The Los Angeles Rams begin their season on Sunday, with a 1:05 p.m. PT home game against the Indianapolis Colts, and you might not recognize them.

The coaching staff is mostly new, save for three holdovers from Jeff Fisher's staff. And when the Rams finalized their 53-man roster on Saturday, 21 of the players on it were not with the team in 2016. The Rams are coming off a 4-12 season in their first year in Los Angeles. They're trying to establish themselves in the nation's second-largest media market and now face competition from the neighboring Los Angeles Chargers.

Change -- drastic change -- was to be expected.

The Rams beefed up their receiving corps, addressed the left side of their offensive line and added depth at linebacker. Over the past five seasons, either 39 or 40 players took at least 100 snaps for them on offense and defense. That equates to 17 or 18 players outside of the starters having a significant impact on a season. Depth is important.

Below is my ranking of each position on the Rams, based on overall talent and depth.

Cooper Kupp was drafted as a slot receiver and left an impression in the preseason. K.C. Alfred/Zuma Press/Icon Sportswire

1. Wide receiver: This position has long been something of a dry well for the Rams, but they did a nice job of addressing it this year. They signed Robert Woods and traded for Sammy Watkins, giving themselves two young, legitimate primary targets. They drafted a slot receiver in Cooper Kupp and a vertical threat in Josh Reynolds, both of whom looked good this summer. And they put themselves in a situation where they don't have to depend on Tavon Austin. He's fourth on the depth chart now, so, anything they get from him is a bonus. Back are Pharoh Cooper and Mike Thomas, who must first serve a four-game suspension. They look good, too.

2. Linebacker: The switch from a 4-3 to a 3-4 under new defensive coordinator Wade Phillips created a need for more linebackers and fewer defensive linemen. On the outside, the Rams have Robert Quinn and Connor Barwin, who have combined for 104 1/2 sacks. Inside are Alec Ogletree and Mark Barron, each of them supremely athletic. The Rams will head into the season with five backups here. A key one is Samson Ebukam, a gifted pass-rusher who was selected in the fourth round of this year's draft. The rest of the group includes three returnees (Matt Longacre, Bryce Hager and Cory Littleton) and another rookie (Ejuan Price).

3. Safety: Rodney McLeod left in 2016 and T.J. McDonald left in 2017, but the Rams are fine here. Lamarcus Joyner is making the transition from slot corner to free safety, a position he excelled at in college. And Maurice Alexander is solidified as the starting strong safety, the spot that suits him best. Joyner is one of at least three Rams safeties who can easily line up at cornerback, in addition to Blake Countess and rookie third-round pick John Johnson.

4. Tight end: The Rams are young here at the top, with second-year player Tyler Higbee and rookie Gerald Everett combining for 11 NFL catches. Their No. 3 tight end, Temarrick Hemingway, who barely even stepped on the field last year, suffered a fractured fibula and will not play this season. But the Rams replaced him by trading for former Washington Redskins tight end Derek Carrier, a veteran heading into his sixth season. Higbee, Everett and Carrier each bring skills and athleticism to the passing game.

5. Defensive line: This ranking includes Aaron Donald, who is currently on the reserve/did not report list. It also excludes Dominique Easley, who tore his ACL again and will be out for the year. Outside of Donald and nose tackle Michael Brockers, the Rams' most experienced defensive lineman is Tyrunn Walker, who started 12 games over the past two years. The rest of the group -- Ethan Westbrooks, Morgan Fox, Tanzel Smart and newcomer Quinton Jefferson -- is unproven to varying degrees.

6. Running back: This position took a hit when Lance Dunbar, brought in largely to catch passes out of the backfield, was placed on the physically unable to perform list. Todd Gurley will carry a heavy workload once again, and the Rams won't need much else if he remains healthy. But Malcolm Brown will nonetheless get a crack at being his backup, after carrying the ball only 22 times over the past two years. And Justin Davis, an exciting undrafted free agent out of USC, is behind him. It'll be interesting to see how much Austin factors into this position.

7. Cornerback: E.J. Gaines was dealt to the Buffalo Bills in the Watkins trade and Troy Hill is suspended for the first two games. Starting opposite Trumaine Johnson, the Rams' franchise corner, will be Kayvon Webster, who didn't see many snaps while playing on loaded Broncos secondaries. The Rams are high on Webster and Nickell Robey-Coleman, who has excelled out of the slot but has been tried out on the outside. Behind them are the lesser-known Kevin Peterson (undrafted free agent in 2016) and Dominique Hatfield (undrafted free agent in 2017). But some of those safeties can help.

8. Offensive line: The Rams did a nice job solidifying the left side of their offensive line, signing left tackle Andrew Whitworth and center John Sullivan while keeping Rodger Saffold as the left guard. But the right side, made up of Jamon Brown and Robert Havenstein, struggled at times in the preseason. And the depth behind them may be lacking. Andrew Donnal is the primary backup with an ability to play tackle and guard, but he has barely practiced because of a knee injury. The Rams also kept tackle Darrell Williams and center Austin Blythe. On Sunday, they were assigned centers J.J. Dielman and Aaron Neary, though Dielman can also play tackle and Neary can also play guard.

9. Quarterback: The Rams stayed young here. Very young. The starter is Jared Goff, who, at 22, will be the NFL's second-youngest starting quarterback. His backup is Sean Mannion, a 2015 third-round pick who has thrown 13 career passes. They both have a lot to prove, especially Goff, who's coming off a horrid rookie season. The Rams cut longtime backup Dan Orlovsky, but they could bring him back after Week 1, when his 2017 salary is no longer fully guaranteed.