All-American-level players at two powerhouse programs, including Arizona junior-to-be Allonzo Trier, decided to stay in school Thursday, making it a very good day for college hoops. 

Trier told ESPN: "I have thought about it for a while, and I have decided to continue my education and basketball career at Arizona. Because of my relationship and faith in Coach [Sean] Miller, the coaching staff and my teammates, I will continue my original goal when I came here -- to help lead the team to a national championship."

For Trier, some of this could be unfinished business. He averaged 17.2 points, 5.3 rebounds and 2.7 assists, but played in only 18 of 37 games after sitting out until Jan. 21 because of a positive drug test (traces of a performance-enhancing substance in his bloodstream). Trier was not projected as a lottery pick, unlike Michigan State's Miles Bridges, who is bypassing big-time guaranteed money to return to East Lansing. Trier almost certainly would have been drafted, though maybe not in the first round.

He's returning to a team that may be as loaded as any Miller has had in Tucson. The Wildcats (32-5) were a 2-seed in last month's NCAA Tournament, losing to Xavier in the Sweet 16. They lose projected top-10 pick Lauri Markkanen, versatile senior Kadeem Allen and freshman combo guard Kobi Simmons, but there's plenty coming back.

Arizona, No. 2 in our Way Too Early Top 25 (and one), returns Trier, Dusan Ristic, Chance Comanche, Parker-Jackson Cartwright and possibly Rawle Alkins, who is still deciding between school and the NBA. The Wildcats are adding 247Sports' No. 3 2017 recruiting class, led by No. 2 overall prospect (No. 1 power forward) DeAndre Ayton, four-star shooting guard Brandon Randolph, four-star center Ira Lee and four-star point guard Alex Barcello.

If Alkins doesn't return, Arizona has its sights on landing one more elite 2017 recruit: five-star forward Brian Bowen. 

It's a big-time roster. Miller has yet to make a Final Four. Given the landscape of the Pac-12 next season, Arizona is set up to win the conference, perhaps with room to spare, boosting its case for a No. 1 seed. The Wildcats will be a universal top-three team in polls, and Trier is the key. He's the program's most important player, and with him back, Miller could have his deepest team ever.