While Mills and Ferguson have played their roles all season, the two Alexanders made their starting debuts and impressed Miles.
Kwon Alexander replaced usual starter Luke Muncie, who was limited to special teams duties because of illness, and finished with four tackles, a forced fumble and a pass broken up.
"I think Kwon Alexander played extremely well for a young guy," Miles said. "I think he plays fast. He certainly wasn't perfect by any stretch. I think he's a guy that will come quickly."
Vadal Alexander started instead of left tackle Josh Dworaczyk as the usual right tackle, Alex Hurst, moved over to left tackle.
"I also agree that [Vadal] Alexander is a guy that has ability that will come. I don't know that his immediate play will be in the same position that Kwon's was."
Dworaczyk said he was working at both tackles spot this week and could play more. Muncie's back from his illness and could return to his linebacker spot.
Even if Dworaczyk, a sixth-year senior, and Muncie, a junior, return to their starting positions, Miles said it's important for the two true freshmen who started last week, and others, to be ready to contribute.
LSU has lost four starters, likely for the season, since August camp for various reasons. In three of the five four, a true freshman has started at least one game since the injury: Vadal Alexander at tackle because the loss of Chris Faulk (knee), Kwon Alexander at linebacker because of the loss of Tahj Jones (academically ineligible), Mills at cornerback because of the loss of Tyrann Mathieu (kicked off team).
"It's imperative that the freshman class contribute," Miles said. "It's a numbers thing for us."
Plenty of playbook left: Miles admitted Monday that there is still a lot of LSU's playbook that fans haven't seen yet. He said if the offense moves the ball consistently, you'll see more wrinkles.
"When you move the ball regularly, you can call a lot of things," he said. "When you aren't hitting on all cylinders, there's an opportunity for you to rein it in because you want to make sure the things that you do are successful."
Miles said that the areas where LSU has struggled to execute -- the passing game, for one, which has had multiple issues -- have had a more limited array of play calls. Another factor, he said, has been a schedule where LSU has had most games in hand early.
"That (additional play calls) is for the future anyway," Miles said. "It was never going to be for those games that you have in hand."
Top 10 tussle: When No. 4 LSU and No. 10 Florida meet Saturday, it'll mark the fourth time in the last seven years when the two teams meet with both ranked in the Top 10.
It happened in 2009 (Florida No. 1, LSU No. 4), 2007 (LSU No. 1, Florida No. 9) and 2006 (Florida No. 5, LSU at No. 9). It never happened in the first 52 games of the series.