It's been a very interesting week for USC's football roster.

On one end of the spectrum, the Trojans have seen 15 players bolt for the transfer portal this month, including a spate of former five-star/Rivals100 prospects over the last week -- former five-star WR/Oklahoma transfer Mario Williams, former five-star quarterback Malachi Nelson, former five-star cornerback Domani Jackson and former top-100 four-star linebacker Tackett Curtis, on top of an earlier five-star transfer departure in all-purpose back Raleek Brown.

And then on Wednesday, four-star Rivals100 wide receiver Ryan Pellum -- the Trojans' highest-rated commit -- announced a National Signing Day flip to Oregon.

Meanwhile, USC announced 19 early signees (with a 20th expected soon in four-star CB commit Isaiah Rubin) while adding a slew of late additions to this 2024 recruiting class over the last week in three-star DE Jide Abasiri (a flip from Minnesota), three-star OLB Lorenzo Cowan (a flip from Kentucky), three-star offensive lineman Kalolo Ta'aga (San Francisco, California) and four-star defensive end Carlon Jones (Bay City, Texas).

The Trojans' class dropped five spots in the Rivals rankings Wednesday to No. 21 (after USC pulled in the No. 7-ranked class last year) and includes just two Rivals100 prospects in four-star cornerback Marcelles Williams (ranked No. 89 nationally) and four-star wide receiver Xavier Jordan (No. 96) along with only one other Rivals250 signee in four-star center Jason Zandamela (No. 216).

But Riley was irrepressibly pleased and encouraged by the Trojans' early signing day haul, while also doubling-down on a message he shared two days earlier in regard to the transfer departures -- this time presumably referencing Pellum's last-minute flip, indirectly.

"If I were to give one comment maybe about this class or I were to sum it up in one way, the commitment level of these guys to understand the opportunity that we all have here at a place like USC, the opportunity to help bring this program back to where we all want it to be, is shared across this class. I mean, you could really feel that with all of the guys, really throughout the process," Riley said. "So many of these guys never wavered, so many of these guys never blinked and they understand really what this means, and I think that's really special.

"And it's something that we, honestly as time has gone on more and more here in the last few years, we have prioritized that just each year I think a little bit more because I think it matters. Because what happens with that is, listen, the guy that wavers on signing day is going to waver when something doesn't go his way here. He's going to waver when he's not the starter as a true freshman coming right out. He's going to waver when somebody on the outside tells him he should look somewhere else. The guys that don't waver and have a passion for being here, they're going to hang in there through the ups and downs, they're going to develop, and then you're going to look up and down the line they're going to turn into really good players -- and a lot of them much sooner rather than later."

Riley covered a lot of ground in his 35-minute press conference. Here were our top takeaways from his comments ...

RELATED: See USC's full 2024 early signing class | Watch Lincoln Riley's full press conference Wednesday | Share your reaction on our Trojan Talk board | See Rivals recruiting rankings

In talking about the early signing class, Riley emphasized the priority he and the staff placed on continuing to add young talent along the offensive line, adding size to the defensive line and adding much-needed help in the secondary.

USC signed five high school offensive linemen for the second year in a row -- four-star center Jason Zandamela (Clearwater, Florida), four-star offensive tackle Justin Tauanuu (Huntington Beach HS), three-star offensive tackle Makai Saina (Arlington, Texas), three-star offensive tackle Hayden Treter (Englewood, Colorado) and three-star offensive tackle Kalolo Ta'aga (San Francisco, California).

Tauannu was a flip from Stanford who committed back on Nov. 10 while Ta'aga committed on Sunday.

"Especially excited about the offensive line," Riley said. "That's been a real focus point. We come in here Year 1 and there's not an offensive lineman in the class, so you knew, we said I think right when I got here, the next few years of offensive line recruiting are going to be really, really important. And we've been pleased with the group that's been here this last year and then excited to add this new group on top of them."

Riley was asked later which recruits he felt didn't get enough attention during the process and he highlighted several of those linemen.

"We signed Lolo here late, [who] we think is – he’s gonna have a little bit of development to do, but certainly when you look at his ceiling and what it can be, is very exciting," Riley said. "I mean, we thought Makai Saina was one of the best offensive linemen that we saw anywhere. Hayden Treter I put in that category as well, guys that were really good players early in their high school career but by the end became dominant players, and you could really see that arc."

Saina was rated a four-star recruit when he committed to USC in June before ending up a three-star.

As for Ta'aga, who at 6-foot-7, 265 pounds had been primarily a basketball player in high school before turning to football this season, Riley expounded on the latest addition to the group ...

“Well, he’s played very little football. I mean, very little football. Maybe the least amount of football of any player I’ve ever signed," Riley said. "But then you turn on the tape, from beginning of the year to end of the year, you see how he moves, you see some of the things. Because, playing offensive line, it’s not a really natural thing for most people. It takes a lot. And so, to see some of the natural movements and some of the things he already does well, considering he’s really only played the game for less than a year – it’s pretty remarkable. Then you see the size and the athleticism.

"And for us, any time you take a guy like that that you know is gonna have some real development to be ready to be able to play at this level, it’s – you get to know the kid. Is he bought in? Is his work ethic, how determined is he at every step of the way? We felt an intense desire by him to be great, and you combine him with one of the best offensive line coaches in the country, that’s a pretty exciting pair.”

On the defensive side of the line, the Trojans made a late push to add edge rushers, flipping 6-foot-6, 270-pound DE Jide Abasiri (Savage, Minnesota) from his Minnesota commitment and 6-foot-3, 220-pound OLB Lorenzo Cowan (Savannah, Georgia) from his Kentucky pledge, as well as reeling in 6-foot-3, 290-pound DE Carlon Jones (Bay City, Texas) all in the last week. (On top of landing Vanderbilt DE transfer Nate Clifton).

"To add the size defensively that we were able to add, I know we've talked a lot about being able to get bigger on the front, being a more physically dominant front, certainly going to be very important as we move forward with [new defensive coordinator D'Anton] Lynn and this coaching staff to be able to establish and develop that," Riley said.

Those additions complement a couple big-time edge rushers the Trojans reeled in earlier in the recruiting cycle in 6-foot-5, 240-pound four-star DE Kameryn Fountain (Atlanta, Georgia) and 6-foo-4, 200-pound four-star OLB Elijah Newby (Cheshire, Connecticut).

"To go get two of our, I agree, two of our favorite players in the class with Kam and with Elijah, I mean, a tremendous job by [OLBs coach Roy Manning], go get two guys across the country, two guys that a lot of people really wanted to sign," Riley said. "I think the key with those, one, is, first, give him a lot of credit identifying two kids and two families that ... are like, about the right things, all the way. Like, I mean, just – the process was as you’d expect it would be. It was competitive, they made their decision, and they never looked back, they never wavered, not for one second. And I give credit to those two kids, to their parents, I give credit to Roy and the relationships that he’s established, and we feel like those are two future difference-makers, and Roy certainly deserves a ton of credit for that.”

And in the secondary, the Trojans had already built a strong class back in the summer with four-star cornerbacks Marcelles Williams (St. John Bosco HS) -- the highest-rated prospect in the Trojans' early signing class -- and Braylon Conley (Humble, Texas) along with four-star safety Jarvis Boatwright (Clearwater, Florida) and three-star safety Marquis Gallegos (Sierra Canyon HS). USC also holds a more recent commitment from four-star cornerback Isaiah Rubin, and although he wasn't announced as a signee Wednesday, Riley intimated he expected that to happen as "a few things are being worked through."

"The secondary was obviously a really big key there as well, and we got a great class so far and a few other things left to happen there," Riley said. "But certainly another piece when you look at what we've had, what we've lost and what we need to replenish and where we need to get better, we knew that was going to be really key as well.

As noted with the aforementioned offensive linemen, Riley was asked which prospects in the class he felt didn't get enough buzz or attention during the recruiting cycle, and he zeroed right in on four-star ATH/LB Desman Stephens II (Clarkston, MIchigan), who committed back on Nov. 23.

Stephens is rated outside the Rivals250.

“Desman comes to mind, defensively. He was still very heavily recruited, but in some ways, I thought undervalued a lot in the recruiting piece," Riley said. "And what happens, and you guys see it, and obviously you guys cover this and see it yourselves is – the guys that get a lot of offers or get a name for themselves as a freshman or a sophomore earlier in their high school career, so many of these guys just kind of ride on that reputation all the way through. But when you go back and really study the tape, yeah, they were good then, but what do they do from, like, the sophomore to the senior year? And then there was so many of the guys, for whatever reason, that are late bloomers – but then you go look at their senior tape and their senior tape’s better than a lot of guys that the outside world would say, ‘Well, they’re ranked higher than this guy.’

"And Desman was one of those guys that we certainly felt that way about. We felt like he was an absolute, I don’t know – steal’s not the right word, because he was still very heavily recruited -- but we were really, really excited about him. That is one of the first ones that comes to my mind."

In addition to the aforementioned offensive lineman, Riley also mentioned Cowan, the OLB from Georgia.

"Lorenzo Cowan comes to mind there – getting Zo today was a great get, his athleticism and what he brings off the edge," Riley said.