A true freshman would have to be very special and cerebral to start in ERob’s 4-2-5, as a lot is asked of those players.
The 4-2-5 is not a “mirror” defense like a 4-3, 3-4, or a 3-3-5, meaning that the offense has a very easy time knowing where the strong side and weak side of the D is at alignment.
Your Sam (strong side) backer has to be a big bodied player but also pretty mobile, as they need to be able to take on linemen, in running situations, pulling guards, etc. However, they also are used in a lot of pass coverage situations as well, so the need to be able to run.
The Will, or weak side linebacker, needs to be able to cover and play in space, with help from the Rover or hybrid safety in run support. This player needs to have a pretty good grasp of what the other team is trying to do, especially with regards to pass concepts.
So for a true freshman to come in and contribute they would have to be physically developed and move in order to play the Sam, or be a hybrid type and understand offensive systems extremely well to play the Will. This isn’t necessarily a defense that tells a linebacker to fill this gap and get the curl in passing situations.
There’s a reason why teams like Georgia. Alabama, etc run it…it’s a great defense against spread offenses. But you need big bodied athletes to play LB in it.
There’s a reason the defense looked better when Barron slid down and played Will and there’s a reason McDonald struggled when asked to do it.
IMO, we will definitely look to add via the portal before next year.