Tough topic to be brief on but here it goes. PM me if you have specific follow up question. Ivys have stepped up their recruiting timeline to high school sophomore year for a very few. This is a major reason I (and others) have suggested that if you know you want to go an Ivy and you are getting offers from D1 P5s and D1 mid-major then take the SAT or ACT in the Spring of sophomore year to give yourself lots of options. Keep in mind, the recruit has to be ready athletically as well as academically (this is the tough part) to get in on the front end. The same rules apply to junior year which is when the majority of the Ivy recruiting activity will take place. The key is exposure and somebody advocating for you (typically the travel or hs coach) in addition to being a genuine D1 prospect with high SATs and ACTs. So if your son was not comfortable taking SAT spring soph year then take early junior year. This gives the prospect more boxes checked when he speaks to an Ivy RC.
Ivy rejection is the trigger. The downshift is starting right now, and the D3 HA coaches and HA showcases are ramping up with roster spots available. This is their time. Lots of folks are at the tail end of Ivy recruiting and realizing it isn't going to happen for one reason or another. Either the board scores weren't high enough for some guys, and they have to recalibrate their choices because D1 scholarship money is gone. The other guys who had high enough ACTs, SATs will be recruited by the D3 HAs. The D3 HA coaches are looking for guys that the Ivys overlooked.
This churn happens every year. The one thing that is different now (from 10 years ago) is the transfer portal and JUCO transfers. This has become the wildcard. So, it becomes real important to understand exactly what these coaches are saying and not saying when on the phone, email, text and in person. Ask lots of specific questions.