EUGENE — There were days during this historic season when Sabrina Ionescu, a national player of the year finalist, was not Oregon’s most dominant player.

In fact, there were plenty of practices when the Ducks’ decorated starting lineup — Ionescu, Maite Cazorla, Lexi Bando, Satou Sabally and Ruthy Hebard — had trouble defending the scout team.

More specifically, defending behind-the-scenes standout Erin Boley.

The 2016 Gatorade national high school player of the year had to sit out games this season after transferring from Notre Dame, but the versatile 6-foot-2 Boley was allowed to practice during the regular season.

“It’s incredible,” Oregon coach Kelly Graves said of having a player of Boley’s caliber pushing the Ducks. “Every day you know that the practice guys or the green squad, whatever you want to call them, always has a great player.

“She is, some days, the best player on the floor. Some days she doesn’t miss.”

Boley averaged 20.7 points, 10 rebounds, four steals, three assists and one block per game during her senior season at Elizabethtown (Kentucky) High.

Last season as a true freshman, Boley played in all 37 games, including 10 starts, averaging 6.5 points and 2.8 rebounds for the Irish. But she never felt truly happy at Notre Dame and decided to transfer after the Irish were knocked out in the Elite Eight of last year’s NCAA Tournament.

If second-seeded Oregon can beat No. 11 Central Michigan in the Sweet 16 on Saturday in Spokane, Washington, there is a good chance the Ducks will face top-seeded Notre Dame in the regional final Monday with a trip to the Final Four on the line.

The Irish (31-3) will play No. 4 Texas A&M in the first regional semifinal Saturday at the Spokane Arena.

“I was just talking to them about that,” Boley said in the locker room after Oregon’s 101-73 victory over Minnesota in the second round Sunday at Matthew Knight Arena. “It will be strange. I wish I was going to be able to play.”

Not being able to practice during the NCAA Tournament or travel to road games throughout the season has been the toughest part about sitting out for Boley.

Graves said the benefits of a developmental year have included improving aspects of her game, like taking defenders off the dribble and running pick-and-roll sets.

“I took it on full steam,” Boley said of her redshirt year. “I knew what I wanted to work on and I knew what I needed to do to push them to get better every day. Sitting out was hard, so practices were like my game days.

“I would always go really hard in our scrimmages because I knew I wasn’t going to get to play. I came and brought my all every day.”

Trying to guard Boley throughout the year assisted in Oregon’s gradual improvement on defense. The Ducks played against some elite players en route to winning the Pac-12 regular-season and tournament championships, but not many who can shoot like Boley.

“She’s been a good scout player for us because she’s a deadeye shooter that gets it off faster than anyone I’ve ever seen shoot the ball,” Ionescu said. “And she’s so efficient, she basically makes every shot she takes.”

The coaching staff believes Boley is capable of playing any position for the Ducks, with the exception of point guard. Oregon is in pretty good shape in that department with Ionescu setting the Pac-12 single-season record for assists, Cazorla taking a lot of the pressure off with her ball-handling skills, and Aina Ayuso creating havoc with her crossover moves off the bench.

Bando, the program’s career leader in 3-pointers, and reserve guard Justine Hall are the only seniors making their final tournament run with the Ducks.

“I think she’ll fit right in,” Ionescu said. “Bando is a hard spot to fill just because of her seniority and her leadership. Erin is going to have to come in and play a different role than she did at her other school and will have to find her minutes and contribute any way she can. … I’m excited to have her on the floor, she’s going to be a great piece for us.”

Ionescu, who was named the USA Today national high school player of year in 2016, is the one who encouraged Graves and the staff to pursue Boley when she opted to leave Notre Dame.

After visiting Oregon, Stanford and Vanderbilt last May, Boley decided to come to Eugene.

“I love this team, they’re like sisters to me,” Boley said. “So it has been amazing to practice with them and watch them grow and get better every day. Honestly, just being able to be their teammate has been so much fun.

“It was the girls and the coaches that sold me. I was looking for a home away from home, and this was it. It’s a true family. A lot of people use that term loosely when they’re recruiting, but it really is. Everyone is so close.”

When all of Oregon’s other players were either competing internationally or getting some rare time off during the first session of summer school last year, Boley and Ionescu were in the practice gym together preparing for the USA under-23 national team tryouts.

“It definitely means a lot,” Boley said of Ionescu wanting her to join forces at Oregon. “She was a great high school player. It was fun in the recruiting process getting to know her and how competitive she was.

“I knew coming here it would be really fun to play with her because she was going to come every day to push me and to compete. I can’t wait to be on the court with her.”

The co-national high school players of the year had already known each other from the Jordan Brand Classic and McDonald’s All-American all-star games.

“When I found out she was transferring, I knew she was a good kid and I talked to her for a little while,” Ionescu said. “She came on her visit here, and we had a good time.”

Boley shot 42.2 percent from the field, 39.5 percent from 3-point distance and 88.9 percent at the free-throw line last season at Notre Dame. She will have three years of eligibility remaining at Oregon.

“That’s really interesting because she is a bigger guard and can really shoot the ball,” Bando said when asked where Boley might fit in on next year’s loaded Oregon roster. “So I could see her playing a guard spot, a forward spot, I see Kelly kind of playing around with where she’ll fit in. But she’s an elite shooter, so she’ll definitely play because of how well she shoots the ball.”

Bando will not get to play with Boley, but she will be rooting for her potential replacement next season. The two top-flight 3-point shooters were roommates this year.

“Erin is awesome. She’s really shy but she’s fun to be around and very sweet,” Bando said. “She takes basketball really seriously. We’ve grown to be really good friends. She’s a great addition to the Ducks.”

In ESPN’s 2016 recruiting rankings, Boley was the No. 5 overall high school prospect, one spot behind Ionescu. Other current Oregon players who were ranked among the top 100 recruits in the class were Hebard, Mallory McGwire, Sierra Campisano and Morgan Yaeger.

“Whatever award Sab didn’t get out of high school, Erin got. So it’s kind of fun,” Oregon assistant coach Jodie Berry said. “She’s not the alpha of the group, she’s just the quiet workhorse that isn’t necessarily going to tell you everything. She’s just going to go out and work hard and not talk about it and do whatever you need to do.”

Boley will be a perfect fit for the Ducks next season because she is already an important part of the tightknit team that Oregon fans have fallen in love with as the program has emerged as a Final Four contender.

“When Erin became available, Sab was like, ‘She’s an amazing person.’ For us, that’s first and foremost,” Berry said. “We want someone who fits in with these guys and has a good time and is a good person. Because not only do we have to spend time with them, but they spend time with our families and help raise our kids.

“So we want good people, and that was the first thing everybody said about Erin, that she’s an amazing person.”